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17 terms

Physics Practice Test

If the mass of bullet equals the mass of the gun
1. A bullet is fired from a gun. The speed of the bullet will be the same as the speed of the recoiling gun
a. Because momentum is conserved.
b. Because velocity is conserved.
c. Because both velocity and momentum are conserved.
d. If the mass of bullet equals the mass of the gun
e. None of these.
2. A cannonball shot from a cannon with a long barrel will have a greater muzzle velocity because the cannonball receives a greater
a. Force
b. Impulse
c. Both of these
d. Neither of this.
1 m/s
3. A rifle of mass 2 kg is suspended by strings. The rifle fires a bullet of mass 1/100 kg at a speed of 200 m/s. What is the recoil velocity of the rifle?
a. 0.001 m/s
b. 0.01 m/s
c. 0.1 m/s
d. 1 m/s
e. none of these
5/6 m/s
4. A 5-kg fish swimming at a velocity of 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is
a. 0.5 m/s
b. 2/5 m/s
c. 5/6 m/s
d. 6/5 m/s
e. 1 m/s
80 J
5. A 2-kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground?
a. 20 J
b. 40 J
c. 60 J
d. 80 J
e. none of these
180 m
6. A car moving at 50 km/h skids 20 m with locked brakes. How far will the car skid with locked brakes if it is traveling at 150 km/h?
a. 20 m
b. 60 m
c. 90 m
d. 120 m
e. 180 m
Slowing down from 100 km/h to 70 km/h
7. Which requires the most amount of work on the brakes of a car?
a. Slowing down from 100 km/h to 70 km/h
b. Slowing down from 70 km/h to a stop
c. Equal amount for either.
Kinetic energy
8. Compared to recoiling rifle, the bullet has a greater
a. Momentum
b. Kinetic energy
c. Both of these
d. None of these
9. If the radius of Earth somehow decreased with no change in mass, your weight would
a. Increase
b. Not change
c. Decrease
d. Not enough information
Both of these
10. If the sun were twice as massive
a. Its pull on the earth would double
b. The pull of the earth on the sun would double
c. Both of these
d. Neither of these.
11. A ring, a disk and a solid sphere begin rolling down a hill together. The one to reach the bottom first is the:
a. Ring
b. Disk
c. Sphere
d. ...They all reach the bottom at the same time
e. Not enough information is given.
12. When a twirling ice skater brings her arms inward, her rotational speed
a. Increases
b. Decreases
c. Remains the same.
Both of these
13. According to the impulse-momentum equation Ft = change in (mv), a person will suffer less injury falling bon a wooden floor which "gives" that on a more rigid cement floor. The "F" in the above equation stands for the force exerted on the:
a. Person.
b. Floor.
c. Both of these.
d. None of these.
Four times as far
14. A car that travels twice as fast as another when braking to a stop will skid
a. Twice as far.
b. Three times as far.
c. Four times as far.
d. Depends on the mass of the cars.
15. An open freight car rolls friction free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, its speed
a. Increases.
b. Decreases.
c. Doesn't change.
d. Impossible to predict.
16. An object is placed exactly halfway between Earth and Moon. The object will fall toward the
a. Earth
b. Moon
c. Neither of these.
No, because the force and the displacement of the object are perpendicular
17. A child is riding merry-go-round. Does the centripetal force acting on a child do work on him?
a. Yes, since a force acts and the object moves, and work is force times distance.
b. Yes, since it takes energy to turn an object.
c. No, because the object has constant speed.
d. No, because the force and the displacement of the object are perpendicular.