Physics Exam #3 MisConceptual Questions

you push a heavy crate down a ramp at a constant velocity. only four forces act on the crate. which force does the greatest magnitude of work on the crate? a. force of friction b. force of gravity c.normal force d. force of you pushing e. net force

a. force of friction

the space shuttle in circular orbit around the earth collides with a small asteroid which ends up in the shuttles storage bay. for this collision, a. only momentum is conserved b. only kinetic energy is conserved c. both momentum and kinetic energy are conserved d. neither momentum nor kinetic energy are conserved

a. only momentum is conserved

a golf ball and an equal mass bean bag are dropped from the same height and hit the ground. the bean bag stays on the ground while the golf ball rebounds. which experiences the greater impulse form the ground? a. the golf ball b. the bean bag c. both the same d. not enough info

a. the golf ball

a ball is thrown straight up. neglecting air resistance, which statement is NOT true regarding the energy of the ball? a. the potential energy decreases while the ball is going up b. the kinetic energy decreases while the ball is going up c.the sum of the kinetic energy and potential energy is constant d. the potential energy decreases when the ball is coming down e. the kinetic energy increases when the ball is coming down

a. the potential energy decreases while the ball is going up

you are lying in bed and want to shut your bedroom door. you have a bouncy "superball" and blob of clay, both with the same mass. which one would be more effective to throw at your door to close it? a. the superball b. the blob of clay c. both the same d. neither will work

a. the superball

an astronaut is a short distance away from her space station without a tether rope. she has a large wrench. what should she dow with the wrench to move toward the space station? a. throw it directly away from the space station b. throw it directly toward the space stations c. throw it toward the station without letting go of it d. throw it parallel to the direction of the stations orbit e. throw it opposite of the direction to the stations orbit

a. throw it directly away from the space station

a car accelerates from rest to 30 km/h. later, on a highway it accelerates from 30 km/h to 60 km/h. which takes more energy, going from 0 to 30 or from 30 to 60? a.0 to 30 km/h b. 30 to 60 km/h c. both are the same

b. 30 to 60 km/h

two balls are thrown off a building with the same speed, one straight up and one at a 45 degree angle. which statement is true if air resistance can be ignored? a. both hit the ground at the same time b. both hit the ground with the same speed c. the one thrown at an angle hits the ground with a lower speed d. the one thrown at an angle hits the ground with a higher speed e. both a and b

b. both hit the ground with the same speed

you push very hard on a heavy desk, trying to move it. you do work on the desk; a. whether or not it moves, as long as you are exerting a force b. only if it starts moving c. only if it doesn't move d. never- it does work on you e. none of the above

b. only if it starts moving

a small boat coasts at constant speed under a bridge. a heavy sack of sand is dropped from the bridge onto the boat. the speed of the boat a. increases b.decreases c. does not change d. without knowing the mass of the boat and the sand, we can't tell

b.decreases

a railroad truck car contains milk and rolls at a constant speed along a level track. the milk begins to leak out the bottom. the car then a. slows down b. speeds up c. maintains constant speed d. need more info about the rate of the leak

c. maintains constant speed

two identical billiard balls traveling at the same speed have a head on collision and rebound. if the balls had twice the mass, but maintained the same size and speed, how would the rebound be different? a. at a higher speed b. at slower speed c. no difference

c. no difference

a bowling ball is dropped from a height h onto the center of a trampoline, which launches the ball back up into the air. how high will the ball rise? a. significantly less than h b.more than h. the exact amount depends on the mass of the ball and the springiness of the trampoline c.no more than h-probably a little less d.cannot tell without knowing the characteristics of the trampoline

c. no more than h-probably a little less

a satellite in circular orbit around the earth moves at a constant speed. this orbit is maintained by the force of gravity between the earth and the satellite, yet no work is done on the satellite. how is this possible? a. no work is done if there is no contact between objects b. no work is done because there is no gravity in space c. no work is done if the direction of motion is perpendicular to the force d. no work is done if objects move in a circle

c. no work is done if the direction of motion is perpendicular to the force

a bowling ball hangs from a 1.0 m long cord. (i) a 200 gram putty ball moving 5.0 m/s hits the bowling ball and sticks to it, causing the bowling ball to swing up; (ii) a 200 gram rubber ball moving 5.0 m/s hits the bowling ball and bounces straight back at nearly 5.0 m/s causing the bowling ball to swing up. describe what happens a. the bowling ball swings up by the same amount in both i and ii b. the ball swings up farther in i than ii c. the ball swings up farther in ii than i d. not enough info

c. the ball swings up farther in ii than i

a baseball is pitched horizontally toward home plate with a velocity of 110 km/h. in which of the following scenarios does the baseball have the largest change in momentum? a. the catcher catches the ball b. the ball is popped straight up at a speed of 110 km/h c. the baseball is hit straight back to the pitcher at a speed of 110 km/h d. scenarios a and b have the same change in momentum e. scenarios a, b, and c have the same change in momentum

c. the baseball is hit straight back to the pitcher at a speed of 110 km/h

when the speed of your car is doubled , by what factor does its kinetic energy increase? a. (2)^1/2 b.2 c.4 d.8

c.4

a man pushes a block up an incline at a constant speed. as the block moves up the incline, a. its kinetic energy and potential energy both increase b.its kinetic energy increases and its potential energy remains the same c.its potential energy increases and its kinetic energy remains the same d.its potential energy increases and its kinetic energy decreases by the same amount

c.its potential energy increases and its kinetic energy remains the same

engines, including car engines are rated in horsepower. what is horsepower? a. the force needed to start the engine b. the force needed to keep the engine running at a steady rate c. the energy the engine needs to obtain from gasoline or some other source d. the rate at which the engine can do work e.the amount of work the engine can perform

d. the rate at which the engine can do work

a truck is going 15 km/h has a head on collision with a small car going 30 km/h. which statement best describes the situation? a. the truck has the greater change of momentum because it has the greater mass. b. the car has the greater change of momentum because it has the greater speed c. neither the car nor the truck changes its momentum in the collision because momentum is conserved d. they both have the same change in magnitude of momentum because momentum is conserved e. none of the above

d. they both have the same change in magnitude of momentum because momentum is conserved

a small car and a heavy pickup truck are both out of gas. the truck has twice the mass of the car. after you push both the car and the truck form the same amount of time with the same force, what can you say about the momentum and kinetic energy of the car and the truck? ignore friction a. they have the same momentum and the same KE b. the car has more momentum and more KE than the truck c. the truck has more momentum and more KE than the car d. they have the same momentum, but the car has more kinetic energy than the truck e. they have the same kinetic energy, but the truck has more momentum than the car

d. they have the same momentum, but the car has more kinetic energy than the truck

a car traveling at a velocity v can stop in a minimum distance d. what would be the car's minimum stopping distance if it were traveling at a velocity of 2v? a.d b.(2)^1/2d c.2d d.4d e.8d

d.4d

a ball is thrown straight up. at what point does the ball have the most energy? ignore air resistance. a. at the highest point of its path b.when it is first thrown c.just before it hits the ground d.when the ball is halfway to the highest point of its path e.everywhere; the energy of the ball is that same at all of these points

e. everywhere; the energy of the ball is the same at all of these points

a small car and a heavy pickup truck are both out of gas. the truck has twice the mass of the car. assume you push both the car and the truck for the same distance with the same force, what can you say about the momentum and kinetic energy of the car and the truck? ignore friction. a. they have the same momentum and the same KE b. the car has more momentum and more KE than the truck c. the truck has more momentum and more KE than the car d. they have the same momentum, but the car has more kinetic energy than the truck e. they have the same kinetic energy, but the truck has more momentum than the car

e. they have the same kinetic energy, but the truck has more momentum than the car