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65 Cards in this Set
- Front
- Back
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Define Motion |
A change in position.
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Define Speed
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How fast or slow someone moves.
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What is the SI unit for speed? |
Meters per a second.
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What is the formula to calculate speed?
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distance/time |
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Explain why speed isn’t usually constant.
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Speed varies from minute to minute. |
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What is instantaneous speed?
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When you go faster and slower.
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What is the formula for calculating Distance?
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speed x time |
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What about the formula for Time?
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distance/speed |
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If you walk 3 kilometers in 30 minutes, what is your average speed in kilometers per hour? (show the set up, answer and unit)
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speed=3/30. Speed=1/10 kilometer per a minute.
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What distance will a truck travel in 3 hours at an average speed of 50 miles per hour?
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150 miles |
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What are the two components of motion?
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Speed and direction.
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Define frame of reference |
http://www.cram.com/flashcards/history-final-exam-8693474
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Explain how children riding on a moving bus may not realize they are moving (unless they look out the window).
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For the children on the bus, if they use other children riding the bus as their frame of reference, they do not appear to be moving. But if they use objects outside the bus as their frame of reference, they can tell they are moving.
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What is your frame of reference if you are standing on the sidewalk and see the bus go by? How can you tell that the bus is moving?
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I can tell that the bus is moving because we are standing still and we see the bus go by us. |
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What are the two components of motion?
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Speed and direction.
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Define velocity
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The measure of both speed and direction |
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Define Vector |
It's a measure that includes both size and direction. |
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How are vectors usually represented? |
They are usually represented with arrows. |
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What is the only way objects can have the same velocity?
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If they are going at the same speed and direction. |
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What is the formula for velocity? |
Speed= distance/time |
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How is the calculation for velocity different than the calculation for speed? |
Velocity involves direction. |
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Another car travels northwest for 2 hours and covers a distance of 90 miles. What is the average velocity of the car?
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45 mph northwest |
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Define acceleration |
a measure of the change in velocity of a moving object.
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A change in velocity may mean a change in what 3 things?
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Speed, direction, or both
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Is slowing down considered a kind of acceleration? Explain.
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Acceleration is the change of velocity; and you do not need to be slowing down in order for a change in velocity to occur.
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Give an example of a kind of acceleration that doesn’t involve a change in speed.
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Going on a merry go round; it has a constant speed.
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What is the formula to calculate average acceleration?
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Final velocity - initial velocity/time |
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What are the SI units for acceleration?
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Meters per second squared |
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What is the acceleration for a runner who went from a standstill to 5m/s in 10s?
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5m/s-0m/s /10 = .5m/s squared
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What is the acceleration for a boat that went from 10mi/h to 60mi/h in 20s?
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60 mi/h - 10 mi/h /20s=2.5 mi/h/s
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Define force
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A push or pull acting on an object.
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What is the reason the motion of an object changes?
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A force is acted upon it |
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How much an object accelerates when a force is applied to it depends on what two things?
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The strength of the force and the object’s mass.
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Force is a vector. What is a vector? |
a measure that has both size and direction.
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Define friction
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The force that opposes motion between any surfaces that keep touching.
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Explain one way friction is helpful and one way friction is harmful.
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When a pen created friction with a piece of paper, friction is helpful because it helps you write. It's harmful when you fall on the ground and your arm creates friction with the ground giving you a scrape. |
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Why do heavier objects have more force? |
Heavier objects press together with greater force, and this causes greater friction between them.
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Rub your hands together quickly for a 20 seconds. What do you feel?Explain why this happens.
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My hands become warmer because the friction causes the molecules on rubbing surfaces to move faster, so they have more energy. This gives them a higher temperature, and they feel warmer. |
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What can be done to reduce friction between the moving parts inside of a car engine?
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To reduce friction, oil is added to the engine. The oil coats the surfaces of the moving parts and makes them slippery.
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What are the 4 types of friction? Give an example of each.
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Sliding: when something is sliding over a surface: when you write with a pencil. Static: when something rests on a surface: when something rests on a surface Rolling: friction that acts on objects when they are rolling over a surface. The wheels of a moving bicycle rolling over the surface. Fluid: friction that acts on objects that are moving through a fluid. Pushing your hand through the water of a pool. |
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What is a fluid? |
A substance that can flow and and take the shape of a container
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What is momentum?
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Property of a moving object that makes it hard to stop.
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What is the formula for momentum?
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Mass times velocity |
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What are the units for momentum? |
Kilograms times m/s |
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State Newton's first law of motion. |
an object at rest will remain at rest and an object in motion will stay in motion unless it is acted on by an unbalanced force.
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What is another name for Newton's first law of motion? |
law of motion is often called the law of inertia because inertia is the tendency of an object to resist a change in its motion. If an object is already at rest, inertia will keep it at rest. If an object is already in motion, inertia will keep it moving.
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What is inertia? |
the tendency of an object to resist a change in its motion.
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Explain how you can use Newton’s First Law to start and stop a skateboard.
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If the skateboard is moving, you can use your foot (unbalanced force) to stop it. If you want the skateboard to move, you can kick it (unbalanced force). |
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What does Newtons Second Law say?
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the acceleration of an object equals the net force acting on the object divided by the object’s mass.
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What is an equation you can use to remember Newton's second law? |
Acceleration=Net force/Mass
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If the net force acting on an object doubles, how will the object’s acceleration be affected?
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The objects acceleration is doubled. |
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State Newton's third law |
every action has an equal and opposite reaction.
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Explain why action, reaction forces don’t cancel each other out.
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Action-reaction forces are equal and opposite forces that act on different objects
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If the action force is you leaning on a wall, what is the reaction force?
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The wall or locker applies an equal and opposite force to you. If it didn’t, you would go right through it or else it would tip over.
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Define gravity |
the force of attraction between things that have mass.
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Give an three examples of things that would not work without gravity. |
rain would not fall, baseballs may never land, the roots of plants would not know which way to grow. |
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What does the Law of Universal Gravitation say? |
gravity is universal and affects all objects in the universe. Universal gravitation means that the force that causes an apple to fall from a tree to the ground is the same force that causes the moon to keep moving around Earth.
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The strength of gravity between any two objects depend of what two factors?
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The objects mass and distance from each other |
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Objects with a greater mass have a ___________________ force of gravity.
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Stronger |
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Objects that are closer together have a __________________ force of gravity.
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Stronger |
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When objects fall to the ground, what causes them to accelerate?
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Gravity |
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What is the rate of acceleration due to gravity?
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9.8 m/s. |
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By t = 1 s, the object is falling at a velocity of 9.8 m/s. What is its velocity by t = 5 s? What will its velocity be at t = 6 s if it keeps falling?
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5s=49 6s=58.8 |
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What if you drop a bowling ball and a basketball at the same time. Which would reach the ground first?
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the bowling ball and basketball would reach the ground at the same time. The reason? The more massive bowling ball is also harder to move because of its greater mass, so it ends up moving at the same acceleration as the basketball. Objects fall at the same rate because of gravity, unless there is more air resistenace in an object.
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Explain why air resistance may affect the rate of acceleration?
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a falling leaf is slowed down by air resistance more than a falling acorn because of the leaf’s greater surface area.
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