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189 Cards in this Set
- Front
- Back
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What is friction?
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The resistive force tha opposes motion of an object past another with it is in contact or through a fluid
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Ways to reduce friction
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put balls on the bottom to roll
add liquid change the texture/ material |
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Three types of friction from greatest to least
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Sliding friction
Fluid friction Rolling friction |
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What is gravity?
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a force that pulls object towards the earth
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What is free fall?
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When the only force acting on a falling object is gravity.
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What is the rate of acceletation due to gravity?
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9.81 m/s squared (10 when working on problem)
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What is terminal velocity?
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The maximum velocity a falling object can achieve.
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When objects speed up air resistance what happens to acceleration?
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It decreases
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During terminal velocity what is the relationship betweem air resistance and the force of gravity of the object?
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They are equal
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What kind of force is there during termical velocity?
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Balanced force (<sum>F=0)
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What is ther different between mass and weight?
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Mass is the quantity of matter in an object; the measurement of inerita.
Weight is the gravitational force exerted on an object by the nearest most massive object. |
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What is the inverse square law?
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The intensity of gravity gets less as the inverse square of the distance.
If the distance increases by 2 times, then the force of gravity is 1/4 |
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How would you explain the universal law of gravitation?
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More mass --> more gravitational pull
Less mass --> less gravitational pull Closer together --> more gravitational pull Farther away --> less gravitational pull Mass and force are directly proportional Distance and force are inversly proportional |
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What is projectile motion?
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An object upon which the only force acting is gravity.
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What are the three types of projectile?
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An object dropped from rest
An object which is thrown vertically upwards An object in which is thrown upwards at an angle |
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What is the one force acting upon a projectile?
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Gravity
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How can an object be moving upwards if the ony force acting upon it is gravity?
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Newtons law suggests that forces are only required to cause an acceleration not a motion.
And in the case of a projectile that is moving upwards there is a downward force and a downwards acceleratation; that is, the objects is slowing down. |
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When is there the highest velocity during projectile?
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When the object is released
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What happens as the object travels upwards?
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Gravity slows the object to 0.
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What happens to the velocity of the object as it travels downwards?
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Gravity increases the velocity
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When is another time when the object has the highest velocity?
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When the object hits the ground.
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The path of a projectile has what two tpes of components?
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horizontal and vertical component.
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The projectile moves forward becaue of ___.
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inertia
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The projectile accelerates downward because of _____.
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Gravity
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A projectiles path is always a ______.
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Parabolic curve
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If three balls are shot horizontally at different speeds, which ball will hit the ground first? Why?
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Each ball will hit at the same time because gravity is independent of horizontal velocity.
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What is work?
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Work is done on an object when a force is exerted on an object that causes the object to move some distance.
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There is no work without ____.
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Motion
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If a person was lifting weights when would they be putting work on them? When would the not?
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They would be putting work on the weights when they lift the weights. (they move) THey would not be doing work on the weights if the weights did not move.
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What is the formula for work?
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Work = Force Distance
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What are the units for force, distance, and work?
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Force- newtons (N)
Distance- meters (m) Work- joule (J) |
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How would you solve this problem: You exert .2-N to lift a pencil off the floor? How much work do you do if you lift the pencil 1.5m?
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.2 1.5 = 3
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What is power?
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The rate at which work is done.
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What is the formula for power?
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Power = work
------- time |
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What is the unit on power?
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Joules per second= Watts
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How would you solve this problem: A figure skater lifts his partner who weight 450-N, 1m in 3-s. How much power is required?
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450 1
---------- = 150-W 3 |
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What is motion?
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An object is considered in motion when its distance from another object changes.
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How can an object be in motion and not be in motion at the same time?
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Because of reference point
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What is a reference point?
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A place or object used for comparison to determine is an object is in motion.
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What is speed?
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The distance an object travels in a unity of time
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What is the formula for speed?
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DIstance
Speed= ------------ time |
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What is velocity?
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Speed in a given direction.
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What is acceleration?
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Rate at which velocity changes
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What is the formula for acceleration?
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final velocity- initial velocity
Acceleration= --------------------------------------- time |
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Who did aristotle study under?
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Plato
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What was Aristotle?
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A philosopher and a scientist
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What did Aristotle say about natural and unnatural motion?
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Natural- Objects natural state is rest
Unnatural- force required to cause motion Heavier objects fall faster than lighte objects. He based his work on observation and logic. |
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What did Galileo say about motion?
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Once and object is in motion no forve is needed to keep it in motion. Force needed to change the motion of an object. The tendency of an object to resister a cahnge in motion is inertia. All objects fall at the same rate. HE based his work on esperimentation.
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Who was proved wrong, Aristotle or Galileo?
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Aristotle
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What are the three types of acceleration?
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Increase velocity (positive values)
Decrease velocity (negative values) Change direction (centripetal acceleration) |
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Is a car that is traveling 50km/hr, goes around a curve, and maintaining a constant speed, accelerating?
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Yes because the verlocity is changing because the direction is changing.
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What is inertia?
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The tendency of an object to resist a change motion
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Inertia depends on ab objects ______.
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Mass
More mass=more inertia=harder to stop/start Less mass = less inertia= easier to stop/start |
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What is Newtons first law?
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An object at rest will star at rest and an object in motion will stay in motion unless acted on by an unbalanced force.
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What is force?
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Any push or pull that can cause an object to accelerate
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What is the unit on force?
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Newtons (N)
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What kind of wuantity is force?
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A vector quantity
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What is net force?
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The combintation of all forces the act on an object (<sum>F)
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What is an unbalanced force?
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an unequal force that changes an objects motion
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What is a balanced force?
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Equal forces acting on ab object in opposite directions, will not cause a change in motion (<sum>F=0)
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What are the two types of balances forces?
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Static / mechanical equilibrium- objects at rest (<sum>F=0)
Dynamic equilibrium- objects moving at a constant velocity (<sum>F=0) moving force = resisting force |
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Why is it harder to get an object moving that is it to keep that object moving once it is in motion?
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To get it movie the force must be greater that the resisting force meaning the net force needs to be greater than 0. To keep it moving the force needs to be = to the resisting force meaning the net force is 0.
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What is Newton's second law?
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Force= Mass Acceleration
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What is the relationship between mass and acceleration?
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Mass and acceleration are inversely proportional. (When one goes up the other goes down- vise versa)
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What is the relationship between force and acceleration?
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Force and acceleration are dorectly proportional. (When one goes up the other goes up-visa versa)
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What is newtons third law?
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For every action there is an equal but opposite reaction.
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Why don't action reaction forces cancel each other out as a balanced force?
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Forces are addded to get a balanced force only if the forces are acting on the same object. Action/ reaction forces are applied to different objects.
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What is a scalar?
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Speed
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What is a vector?
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A measurement and a direction
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What are the 3 ways machines make work easier?
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Change the amount of force you exert (multiply force)
Change the distance over which you exert force (multiply distance/ speed) Change the direction in which you exert force |
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Do machines change the amount of work done?
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NO!!!
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There is a _____ when using a machine
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tradeoff
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If a machine allows you to apply a smaller force the distance will _____.
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increase
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If a machine reduces the distance the force will _____.
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increase
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If a machine allows you to apply a force in a different direction it doesnt change the amount of ____ or ____ you have to apply.
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Force/ Distance
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What is mechanical advantage?
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The number of times a force is exerted on a machine is multiplied by the machine.
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Formula for mechanical advantage
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MA = Output force
------------------ Input force |
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If MA > 1 machine multiplies the ______.
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output force
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If MA < 1 machine multiplies the _________.
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Output distance
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If MA = 1 ______.
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Changing direction
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What is efficiency?
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Efficiency compared the output work to the input work (%)
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What is the formula for efficiency?
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Efficiency = Output work
------------------ 100 input work |
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Can the efficiency be greater thatn 100%?
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NO!
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Is efficiency usually < or > 100%?
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< (less than)
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What are the 6 simple machines?
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Lever
Pulley Inclined plane Wheel and axel Wedge Screw |
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Scientific method and experimentation
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1. Determine problem
2. Gether information 3. Make a hypothesis 4. Test the hypothesis 5. Gather Data and observations 6. Analyze the results 7. Draw a conclusion |
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Why must all experiments be controlled?
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It will cause unreliable results
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What does an experiment mean when it is being controlled?
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All conditions are kept the same except for the two variables being tested.
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What are the 4 different variables?
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•Independent variables
•Dependent variables •Control •Limiting variable |
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What is an independent variable?
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What is being tested? The vaiable that you minipulate or change.
What you are controlling/ cause |
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What is a dependent variable?
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Variable affected by the independent variable.
The results/ effect |
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What is a control?
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A standard comparison for checking and verifying resluts in an experiment
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What is a limiting variable?
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A variable that must be controlled in order to collect reliable information.
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What are the Independent variables, dependent variables, control, and limiting variables in this example?: What music (classical/ pop/ rock/ R&B/ rap) helps students concentrate better while studying?
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Independent; type of music
Dependent: student concentration, Control: Test with no music Limiting: the test, volums of music, time, music preference, location of experiement, temperature, etc. |
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What is an observation?
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Using your senses to gether accurate and detailed information about something
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What can be used to gether more accurate data?
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Instruments: microscope balance etc.
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What are the two different types of observations?
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Quantitative and qualitative
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What is a quantitative observation?
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Numerical amount, observation that includes some sort of measurement.
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What is a qualitative observation?
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An in depth description characteristic of what is being observed
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What is an inference?
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Conclusions based on your observations and prior knowledge
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What is the mean?
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A measure of the average of a number of quantities (average)
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What is the median?
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The middle number of an ordered group of numers.
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What is the mode?
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Element that appears most frequently in a group of numbers
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What is the range?
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A numerical difference between the highedt and lowest data point.
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What are the 4 types of graphs?
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•Line graph
•Bar/column graph •Pie/ doughnut graph •Area graph •Scatter graph |
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What does a line graph show?
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Progressions, trends, relationships (time column)
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What does a bar/column graph show?
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comparisons and trends
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What does a pie/doughnut graph show?
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Percentages
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What does an area graph show?
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Comparisons
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What does a scatter graph show?
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Variable date (best fit line) components of a graph
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What must all graphs have?
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•Titles
•Units •Lables •Key |
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What is the measurement for mass?
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grams
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what instrument do you use to measure mass?
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Triple beam balance
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What is the unit of measurement you use to measure volume?
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Liters
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What instrument do you use to measure volume?
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Graduated cylinder
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How do you find the measure of regular shaped object?
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Length X width X height
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How do you find the volume of irregular shaped objects?
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Use the smallest graduated cylinder possible. (you must know the increments of the cylinder)
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How many cm does 1 mL equal?
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1 mL=1cm
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What is the unit on density?
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Unit depends on mass and volume.
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How do you find density?
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Mass/ volume
g/mL |
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What is the metric system based on?
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Powers of ten
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Giga
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10 (9)
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Mega
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10 (6)
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Kilo
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10 (3)
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Hecto
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10 (2)
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Deka
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10 (1)
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Deci
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10 (-1)
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Centi
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10 (-2)
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Milli
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10 (-3)
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Micro
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10 (-6)
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Nano
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10 (-9)
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Pico
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10 (-12)
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Symbol for Giga, Mega, Kilo, Hecto, Deka
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Giga- G
Mega-M Kilo- k Hecto- h Deka- da |
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Symbol for deci, centi, milli, micro, nano, pico
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deci- d
centi- c milli- m micro-µ (alt-m) nano- n pico- p |
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What is the basic unit of measuremtnt for length?
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meters
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What is the symbol and measurement for pico?
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measurement: 10 (-12)
symbol: p |
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What is the measurement and symbol for Tera?
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Measurement: 10 (12)
symbol: T |
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What is the measurement and symbol for femto?
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Measurement :10 (-15)
symbol: f |
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What is rhe difference between a beaker and a graduated cylinder?
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Beaker HOLDS liquid
Graduated cylinder MEASURES liquid |
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The + and - for acceleration mean...
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+ I -
--------------------------I--------------------------------- velocity increases I velocity decreases Increases speed I decreases speed IF IF object is going I object is going in + in + direction I direction |
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What is chemistry?
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The scientific study of structures, properties, and reactions of the chemical elements and teh compounds they form. (the study of matter and the transforms it undergoes)
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What is matter?
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Anything that occupies space
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What is an atom?
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Basic building block of matter
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Who first proposed atoms and when?
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Democritus in 500B.C.
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What are subatomic particles?
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Protons neutrons and electrons
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What is contained in the atomic nucleus?
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Nucleons (protons and neutrons)
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What are protons?
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Positively charges particles in the atomic nucleus (p+)
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What are neutrons?
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electrically neutral part in an atomic nucleus (n(0))
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What are electrons?
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Negatively charges particles in an atom (e-)
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Who discovered the "plum pudding" (electron suspended in positively charged field)?
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J.J. Thompson
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Who discovered that positively charge and most of mass contained in nucleus electrons orbit around the nucleus?
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Rutherford (1911)
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Who discovered that electrons orbit the nucleus in successive orbital shells based on energy levels, "quantized" shells?
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Bohr (1913)
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Who discovered the "electron clouds" similar to shells, and the electrons travel in waves?
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Schrodinger (1926)
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What are elements?
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a fundemental material consisting of only one type of atom.
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Who organized the periodic table?
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Dimitri Medeleev (1869)
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How many groups and periods are in the Periodic table?
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7 periods- all elecemts in same period have same # of atomic shells?
18- groups- properties in the same group are all similar |
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What does the atomic symbol tell you?
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Designated elemtent
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What does the atomic number tell you?
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# of protons in the nucleus
# of protons = # of electrons |
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What deos the mass #/atomic weight tell you?
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Total # of protons and nuetrons (# of nucleons)
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What deos the mass #/atomic weight tell you?
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Total # of protons and nuetrons (# of nucleons)
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What are isotopes?
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Atoms who nuclei have the same # of protons but different # of nuetrons
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What are the subshells and how many electrons can they hold?
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s-2
p-6 d-10 f-14 |
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what is valance e-?
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Number of electrons in the outer most shell.
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What are characteristice of metals?
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luster, opaque, high desity and good conductors of electricity and heat
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what are characteristice of nonmetals?
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Poor conductors of heat and electricity, can be transparents and are not ductile or malleable
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What are metalloids?
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Have charcteristics of metals and non-metals, also called semi conductors
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In the periods does the size increase or decrease from left to right?
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Decrease (same period same # of atomic shells)
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IN a group does the size increase or decrease from top to bottom?
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increase (some group = same valence)
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What are charactedistics of alkali metals?
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1 e- in outter most shell, used for soaps, very reactive, may even explode in water
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What are characteristice of alkaline- earth metals?
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2 e- in outtermose shell, fire-resistant
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What are characteristics of transition metals?
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less reactive with water thatn alkaline metals, used for sturcture use in technology
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What are characteristics of Chalcogens?
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6 e- in outtermost shell, form ores
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What are characteristics of halogens?
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7 e- in outter shell, for salts, oftern react with metal
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What are characteristice of noble (inert) gasses?
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8 e- in outter shell, non-reactive gasses
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What are the types of chemical reactions?
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Sythesis
Decomposition Single Displacement Double Displacement |
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Synthesis
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Two or more compounds formed to make a more complicated one.
A+B=AB |
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Decomposition
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The opposite of synthesis- a complex molecule breaks down to make more simpler ones.
AB=A+B |
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Single Displacement
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One element trades places with another element in a compound.
A+BC=AC+B |
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Double Displacement
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Anions and cations of two different molecules switch places, forming two entirely different compunds.
AB+CD=AD+CB |
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IN a chemical equation what does -----> mean?
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yields or produces
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What are products?
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Newly formed substances (right of arrow)
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What are reactants?
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Chemicals that react together (on the left side of the arrow)
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What are compounds?
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2 or more dofferent elementts combines chemicalls. (usually with different propwerites than the elemts indavidually)
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What is the law of conservation of mass?
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Mass cannot be destroyed or created during any chemical change. The mass you start with is always the same as the mass you end with.
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What is chemical change/ chemical reaction?
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When the atons of a substance are rearrangsd. (required new substance to have a chemical composition are different from original one)
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What is a physical change?
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A change in which the shape, size, or physical state is changed but chemical composition is the same
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What are physical properties?
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Color, odor, density, hardness, sturcture, solubility, melting point, boiling point etc.
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What are chemical properties?
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Combos od acids and bases, reactions with oxygen and other active gasses (it is determined by the reaction or substances)
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What are molecules?
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Two or more atoms joined by chemical bonds
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