PY- 131 Exam 1

A 2 kg mass has 40 J of potential energy with respect to the ground. Approximately how high is it above the ground? a. 2 m b. 3 m c. 1 m d. 4 m e. none of these

A

A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy that is a. more than 40 J. b. 40 J. c. less than 40 J. d. impossible to predict without additional information

A

A girl pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagon's acceleration in meters per second? a. 3,0 b. 300 c. 10 d. 0.3 e. 30

A

A hockey puck is set in motion by stormy at the PNC Arena. If ice friction and air neglected, the force required to keep the puck sliding at constant velocity is a. zero b. equal to its weight. c. equal to the product of its mass times its weight. d. equal to its weight divided by its mass.

A

A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is a. 400 N. b. none of these c. 1600 N. d. 200 N. e. 800 N.

A

If the speed of a moving object doubles, which of the following also doubles? a. all of these b. kinetic energy c. momentum d. acceleration

A

The force of an apple hitting the ground depends upon? a. the speed of the apple just before it hits. b. all of these c. whether or not the apple bounces. d. the time of impact with the ground.

A

The gain in speed each second for a freely-falling object is about a. 10 m/s. b. o. c. 20 m/s. d. 5 m/s. e. depends on the initial speed

A

Whereas impulse involves the time that a force acts, work involves the a. distance that a force acts. b. acceleration that a force produces. c. time and distance that a force acts.

A

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of a. 2 kg m/s. b. 0 kg m/s. c. 5 kg m/s. d. 1 kg m/s. e. more than 5 kg m/s.

B

A car moves 4 times as fast as another identical car. Compared to the slower car, the faster the car has a. 12 times the KE. b. 16 times the KE. c. 8 times the KE. d. 4 times the KE.

B

A car that travels twice as fast as another when breaking to a stop will skid a. depends on the mass of the cars b. four times as far. c. twice as far.

B

A scientific statement that can never be changed is a scientific a. theory. b. none of these choices are correct. c. law. d. hypothesis e. principle.

B

An object's weight may properly be expressed in units of a. kilograms. b. newtons. c. cubic centimeters d. meters.

B

If an object's mass is decreasing while a constant force is applied to the object, the acceleration a. remains the same. b. increases. c. decreases.

B

If you push an object twice as far while applying the same force, you do a. the same amount of work. b. four times as much work. c. half as much work. d. twice as much work.

B

If your automobile runs out of fuel while you are driving the engine stops but you do not come to an abrupt stop. the concept that most explains why is a. resistance. b. inertia. c. acceleration. d. gravity.

B

A ball is moving at 3 m/s and has a momentum of 48 kg m/s. What is the ball's mass? a. 4 kg b. none of these c. 16 kg d. 12 kg e. 144 kg

C

A clerk can lift containers a vertical distance of 1 meter or can roll them up a 2 meter-long ramp to the same elevation. With the ramp, the applied force required is about a. four times as much. b. twice as much. c. half as much. d. the same.

C

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to a. revolve in a smaller circle b. increase its speed c. follow a straight-line path. d. continue to follow a circular path.

C

You are kidnapped by some political science major because you said it was not a real science. They blindfold you in the car but you are able to judge the speed of the car by the sound of the engine (yes, you are that good). A car maintains a constant velocity of 100 km/hr for 10 seconds. During the interval its acceleration is a. 110 km/hr. b. 1000 km/hr. c. 10 km/hr. d. zero

C

A ball rolling down an incline has its maximum kinetic energy at a. three-quarters of the way down b. the top c. halfway down. d. the bottom.

D

A bullet is fired from a gun. The speed of the bullet will be about the same as the speed of the recoiling gun a. none of these b. if the mass of the bullet equals as the mass of the gun. c. because velocity is conserved. d. because both velocity and momentum are conserved. e. because momentum is conserved.

D

Disregarding air resistance, objects fall with constant a. velocity. b. speed. c. distances each successive second. d. acceleration.

D

If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting position is about a. 10 seconds. b. not enough information to estimate c. 20 seconds. d. 2 seconds. e. 1 second.

D

It is correct to say that impulse is equal to a. the change in momentum. b. velocity multiplied by time c. the force multiplied by the distance the force acts. d/ momentum.

D

Joe pushes bill, who is asleep, bill a. will inevitably punch Joe in the arm when he wakes. b. does not push even after he wakes up. c. pushes Joe immediately, but not as hard. d. pushes Joe equally hard even without waking up

D

The force required to maintain an object at a constant velocity in free space is equal to a. the mass of the object. b. the weight of the object. c. the force required to stop it. d. zero. e. none of these

D

A 1-kg mass at the earth's surface weighs a. none of these b. 4.9 N. c. 9.8 N. d. 10.8 N. e. 1 N.

E

A 1000-kg car moving at 10 m/s brakes to a stop in 5 s.The average braking force is a. 5000 N. b. 1000 N. c. 3000 N. d. 4000 N. e. 2000 N.

E

A 5-kg shark swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish named Nemo who is swimming toward it at 4 m/s. the speed of the shark after this meal is a. 1/5 m/s. b. 1/6 m/s. c. 1/2 m/s. d. 2/3 m/s. e. 3/2 m/s.

E

A heavy and a light object released from the same height in a vacuum have equal a. momenta. b. accelerations. c. weights. d. kinetic energies. e. none of these

E

An object lifted 10 meters gains 200 J of potential energy. If the same object is lifted 20 meters, its potential energy gain is a. the same. b. four times as much. c. more than four times as much. d. half as much. e. twice as much.

E

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is a. 60 km/h/s. b. 3 km/h/s. c. 10 km/h/s. d. 600 km/h/s. e. 6 km /h/s.

E