Physics Test 2

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 80J B 6J C 8J D 32J E none of these

A

A heavy truck and a light truck roll down a hill. Neglecting friction, at the bottom of the hill, the heavy truck will have greater A kinetic energy. B speed. C both of these. D none of these.

A

A hydraulic press, like a wheel and axle, is capable of multiplying force input. A always true B always false C sometimes true D sometimes false

A

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. The recoil velocity of the rifle is about A 1 m/s. B 0.001 m/s. C 0.01 m/s. D 0.1 m/s. E none of these

A

An upright broom is easier to balance when the heavier end is A highest, farthest from your hand. B nearest your hand. C same either way.

A

If you do twice the usual work on an object in half the usual time, your power output is A quadruple the usual power output. B twice the usual power output. C the usual power output. D one half the usual power output. E one fourth the usual power output.

A

Two billiard balls of the same mass roll straight toward each other. The first has a velocity of +5 m/s and the second has a velocity of -3 m/s. Aer colliding, the first ball has a velocity of A -3 m/s. B +3 m/s. C -5 m/s. D +5 m/s. E +2 m/s.

A

Two pool balls, each moving at 2 m/s, roll toward each other and collide. Suppose aer bouncing apart, each moves at 4 m/s. This collision violates conservation of A energy. B momentum. C both momentum and energy. D none of the above choices

A

When a twirling ice skater brings her arms inward, her rotational inertia A decreases. B increases. C remains the same.

A

A car travels in a circle with constant speed. The net force on the car is A directed forward, in the direction of travel. B directed towards the center of the curve. C zero because the car is not accelerating. D none of these

B

A jack system will increase the potential energy of a heavy load by 400 J and generate 600 J of heat with a work input of 1000 J. The eiciency of the jack system is A 25%. B 40%. C 60%. D 100%. E Not enough information is given.

B

Acrobat Bart at the circus drops vertically onto the end of a see -saw, with his partner Art equidistant from the fulcrum at the other end. Art is propelled straight upward a distance twice that of Bartʹs dropping distance. Neglecting ineiciencies we see A the masses of Art and Bart are equal. B Art has half the mass of Bart. C Bart has half the mass of Art. D need more information

B

Centrifugal forces are an apparent reality to observers in a reference frame that is A at rest. B rotating. C an inertial reference frame. D moving at constant velocity. E none of these

B

How long will it take to stop a 1500 kg car moving at 20 m/s with a braking force of 6000 N? A 0.2 s B 5s C 50s D 80s

B

To do 10 J of work pushing a crate using 2 N of force, you will need to push the crate A 0.2 m. B 5m. C 10 m. D 20 m.

B

Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr? A the 30 km/hr car B the 60 km/hr car C Both have the same kinetic energy. D More information is needed about the distance traveled.

B

Which jar will roll down an incline in the shortest time, an empty one or one filled with peanut butter? A the empty jar B the filled jar C both reach the bottom at the same time D need more information

B

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5 -kg bowling ball that is initially at rest on a frictionless surface. The speed of the putty thereaer is A 1/4 m/s. B 1/5 m/s. C 1/6 m/s. D impossible to solve with the information given.

C

If you need to tighten a bolt with 80 Nm of torque using a wrench with a handle that is 25 cm from the axis of the bolt, how much force do you need to apply when turning the wrench? A 20N B 80N C 320 N D 2000 N

C

Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second when you are riding the bicycle, then your speed will be A 0.5 m/s. B 1 m/s. C 2 m/s. D 3.14 m/s.

C

The center of mass of a human body is located at a point A which is fixed, but dierent for dierent people. B that is always directly behind the belly button. C that changes as a person bends over. D none of these

C

Two 1 kg billiard balls roll toward each other, each moving with speed 10 m/s. What is the combined momentum of the two balls? A 10 kg m/s B 20 kg m/s C 0kgm/s

C

Your pet hamster sits on a spinning record player. If the angular speed of the record player doubles and he moves to a point half as far from the center, then his linear speed A doubles. B halves. C remains the same. D quadruples. E is one fourth as much.

C

How can you increase the angular momentum of a ball spinning on a string? A increase the length of the string B spin the ball faster C spin the ball for a longer time D A) and B) E all of the above

D

How much work is done on a crate as it slides 10 m across the floor at a constant velocity of 2 m/s? A 20J B 5J C 40J D 0J E not enough information

D

The famous Leaning Tower of Pisa doesnʹt topple over because its center of gravity is A displaced from its center. B in the same place as its center of mass. C relatively low for such a tall building. D above a place of support. E stabilized by its structure.

D

When trying to turn a stubborn screw, you can generate twice as much torque by switching to a screwdriver with a handle that is A half as long. B twice as long. C half as wide. D twice as wide. E none of these.

D

A car moving at 50 km/hr skids 20 m with locked brakes. How far will the car skid with locked brakes if it were traveling at 150 km/hr? A 20m B 60m C 90m D 120 m E 180 m

E

A large heavy truck and a small baby carriage roll down a hill. Neglecting friction, at the bottom of the hill, the baby carriage will have a greater A speed. B acceleration. C momentum. D all of these E none of these

E

A longer cannon barrel is advantageous because it increases A impulse delivered to the ball by allowing the force to be applied for a longer time. B impulse delivered to the ball by applying a larger force. C the ballʹs momentum by increasing its velocity. D AandB. E AandC.

E

A woman alleviates her back pain in the fih month of pregnancy by wearing a backpack instead of carrying a purse. When the pain resurfaces in the ninth month of pregnancy, she can reduce the back pain once again by A walking in snowshoes. B adding a few books to her backpack. C hanging the backpack from the end of a stick carried over her shoulder. D delivering the baby. E all of the above.

E

In class, I laid on a bed of nails with cinder blocks stacked on top of me. When Thomas struck the blocks with the sledgehammer, the kinetic energy of the hammer went into A kinetic energy of the flying cement fragments. B heating up the cement fragments. C kinetic energy of me being driven onto the nails D breaking the blocks apart. E all of the above.

E

When a car is braked to a stop, its kinetic energy is transformed to A energy of motion. B energy of rest. C potential energy. D stopping energy. E heat.

E