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61 Cards in this Set
- Front
- Back
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How does velocity differ from speed?
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Velocity-Vector
(includes direction) Speed-Scalar |
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How does average velocity differ from istantaneous velocity?
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average is taken over period of time; instantaneous is one given moment
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What is acceleration?
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rate at which velocity changes
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Can you accelerate at a constant speed?
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yes, while turning
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What does it mean to be in free fall?
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only force on you is gravity
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What is the acceleration of an object in free fall?
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9.8 m/s(squared)
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What is the initial velocity of a dropped object?
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0
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When is the equation d=vt used? When is d=(1/2)at(squared) used?
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d=vt-when speed is constant
d=(1/2)at(squared)-speed is changing, when initial velocity is zero |
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What is the difference between a vector and scalar?
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vector-measurement w/ direction
scalar-measurement w/o direction |
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Why doesn't gravity slow a ball down that's rolling on the ground?
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gravity is a vertical force, does not affect horizontal motion
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Does gravity affect the hoizontal motion of a projectile?
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No
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If you drop a bullet and fire a bullet from a horizontal rifle simutaneously, which bullet will hit the ground first? Why?
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same time, b/c same initial vertical velocity
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What is Newton's first law? (inertia)
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an object at rest will stay at rest, an object in motion will stay in motion unless acted upon by an outside force
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How does intertia relate to seatbelts? Headrests?
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seatbelts-object in motion will stay in motion(deccelerating)
headrests-object at rest will stay at rest(accelerating) |
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What are mass and weight? Describe units, vector/sclar, and key differences.
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Mass-scalar, kg, measure of an object's inertia or matter in an object
Weight-vector, N, gravitational pull on an object |
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Why do scientists prefer mass to weight?
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mass is universal
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What is equilibrium? What is the net force?
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when net force is 0 N
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Is an object at a constant velocity in equilibrium?
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Yes
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What is the upward force that keeps a book on a table in equilibrium?
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normal/support force
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What is Newton's second law?
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net force on an object causes acceleration that is proportional to force and inversely proportional to the mass; same direction as net force
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What is the relationship between force and acceleration?
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directly proportional
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What is the relationship between mass and acceleration?
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inversely proportional
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What is friction?
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resistive force of two objects' grip
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What is the relationship between force and pressure?
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directly proportional
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What is the relationship between area and pressure?
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inversely proportional
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Summarize Newton's third law.
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every force causes an equal and opposite reaction force
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What is momentum?
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measure of an object's forward progress
p=mv |
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What is the momentum of an object at rest?
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0
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Is momentum conserved?
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Yes
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What type of collision causes two objects to hook together?
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completely inelastic
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What is work? Give the units.
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changing an object's energy, joules
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Can someone do work on an object at rest?
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No
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What is the relationship between power and time?
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inversely proportional
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What are the two types of mechanical energy?
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kinetic and potential
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What is kinetic energy?
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energy of motion
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When an object doubles its speed, what happens to the kinetic energy?
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quadrupoles
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Is energy conserved?
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Yes
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How is energy lost?
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heat because of friction and air resistance
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What is the difference between rotational and tangential speed?
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rotational-rotations/time
tangential-distance/time |
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What is centripetal?
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inward
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What happens if CG extends over support base?
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object topples
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What does universal gravity mean?
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all objects in the universe exert forces on each other
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Why doesn't the earth crash into the sun due to gravity?
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great tangential speed
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Why was Cavendish's discovery important?
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enabled the discovery of the mass of the earth
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Why do objects in orbit float?
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in free fall
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What is an atom?
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substance w/ same # of protons
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What are the four phases of matter?
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plasma, gas, liquid, solid
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What is the SI unit of charge?
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coulomb (C)
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What is coulomb's law?
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F=[kq(1)q(2)]/d(squared)
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Give an example of a solid w/ a crystal structure?
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ice, salt, sugar, etc...
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Give an example of an amorphous solid?
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glass
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What is the relationship between volume and density?
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inversely proportional
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Does liquid pressure push down on an object only from above?
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no, all sides
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How can a dam holding back a small pond be under more pressure than a dam holding back Lake Superior?
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if it is deeper
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Is upward pressure on the bottom of an object the same as downward pressure on the to?
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no, upward pressure is greater because pressure increases w/ depth
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What is buyant frce?
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upward force on immersed obct
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What is the buoyant force equal to? What principle is this?
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weight of fluid displaced; Archimedes'
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Does buoyant force increase with depth?
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no
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Can you change a liquid's volume or density?
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no, it cannot be compressed like a gas
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What is Boyle's law?
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pressure and volume of a gas are inversely proportional
P(i)V(i)=P(f)V(f) |
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What is Bernouilli's Priciple?
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as speed of fluid increases, pressure decreases
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