Physical Science

11. A girl pushes a cart to the left with a 100-N force. At the same time a boy pushes it to the right with a 50-N force. The net force exerted on the cart is A) 50 N to the left. B) 50 N to the right. C) 100 N to the left. D) 100 N to the right.

A

15. A pair of 3-N and 4-N forces CANNOT have a resultant of a) 0 N. b) 1 N. c) 7 N. d) But it can have any of the above.

A

18. Burl and Paul have a total weight of 1300 N. The tensions in the ropes that support the scaffold they stand on add to 1700 N. The weight of the scaffold itself must be A) 400 N. B) 500 N. C) 600 N. D) 800 N.

A

20. A parachutist falling at constant velocity is in a state of A) dynamic equilibrium. B) non-dynamic equilibrium. C) being in and out of dynamic equilibrium. D) none of the above

A

36. A ball rolls along equal-length tracks A and B. It will reach the end of track B a) sooner than along track A. b) at the same time as along track A. c) later than along track A. d) None of these make sense

A

40. An object travels 8 m in the 1st second of travel, 8 m again during the 2nd second of travel, and 8 m again during the 3rd second. Its acceleration is A) 0 m/s2. B) 5 m/s2. C) 8 m/s2. D) 10 m/s2.

A

A 10-kg block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block is A) 1 m/s2. B) 2 m/s2. C) 5 m/s2. D) 10 m/s2

A

A ball is thrown upward and caught when it returns. When air resistance affects the ball, compared with the initial upward speed, the speed of the ball when caught is A) less. B) the same. C) more

A

A car by itself is capable of a certain maximum acceleration. When it tows a car of the same mass, its maximum acceleration is A) half. B) one-third. C) one-fourth. D) the same

A

A constant net force acts on an object. Describe the motion of the object A) Constant acceleration B) Constant speed C) Constant velocity D) Increasing acceleration

A

A heavy parachutist has a greater terminal speed compared with a light parachutist with the same size chute, because the heavier person a) has to fall faster for air resistance to match his weight. b) is more greatly attracted by gravity to the ground below. c) has a greater air resistance. d) has none of the above.

A

A hockey puck slides across a frozen pond. If ice friction and air resistance are neglected, the force needed to keep the puck sliding at constant velocity is A) 0 N. B) equal to the weight of the puck. C) the weight of the puck divided by the mass of the puck. D) the mass of the puck multiplied by 10 m/s2. E) none of the abov

A

A net force F acts on a mass m and produces an acceleration a. What acceleration results if a net force 2F acts on mass 4m? A) a/2 B) 8a C) 4a D) 2a

A

An object that has twice as much mass as another object also has twice as much A) inertia. B) velocity. C) gravitational acceleration. D) volume. E) all of the above

A

If the mass of an object decreases to half, and its speed doubles, its momentum a) remains unchanged. b) is doubled. c) is quadrupled. d) decreases.

A

The force required to maintain an object at a constant velocity in free space is equal to A) zero. B) the mass of the object. C) the weight of the object. D) the force required to stop it

A

What is the speed of a 4-kg ball with a momentum of 12 kg∙m/s? A) 3 m/s B) 4 m/s C) 12 m/s D) 48 m/

A

When Galileo rolled a ball down an incline and up another incline, he found that the ball rolled nearly to A) its initial height. B) halfway its original height. C) three-quarters its original height. D) higher than its original height

A

When a 10-kg block is simultaneously pushed eastward with 20 N and westward with 15 N, the acceleration of the block is a) 0.5 m/s2 east. b) 0.5 m/s2 west. c) 0.5 m/s2 east-west. d) None of the above.

A

When you simultaneously drop a light tennis ball and a heavy bowling ball, they hit the floor A) at the same speed. B) with the same force. C) with the same momentum. D) all of the above

A

You are standing in a moving bus, facing forward, and you suddenly fall forward. You can imply from this that the bus's A) Velocity decreased. B) Velocity increased. C) Speed remained the same, but it's turning right. D) Speed remained the same, but it's turning left.

A

10. A baseball weighs 1.5 N on Earth. Another type of ball weighs 1.5 N on the Moon. The ball with the greater mass is the A) baseball. B) other type of ball. C) same for each. D) not enough information

B

12. An object is pulled with two forces, 10 N northward and 15 N southward. The magnitude of the net force is A) 0 N. B) 5 N. C) 10 N. D) 15 N. E) none of the above

B

17. Whenever the net force on an object is zero, its acceleration A) may be zero. B) is zero. C) and velocity are the same. D) none of the above

B

19. A bucket of cement is raised by a rope at constant speed at a construction site. Compared with the force of gravity on the bucket, the upward force supplied by the rope is A) greater. B) equal. C) less

B

22. An 800-N man stands at rest with his weight evenly distributed on two bathroom scales. The reading on each scale is A) 200 N. B) 400 N. C) 800 N. D) 1600 N. E) none of the above

B

23. In general, the friction forces between one object and another act A) in the same direction. B) in opposite directions. C) at right angles to each other. D) none of the above

B

27. The difference between speed and velocity mostly involves a) amount. b) direction. c) acceleration. d) All of the above

B

28. The kind of speed you read on a speedometer is a) average speed. b) instantaneous speed. c) changing speed. d) constant speed.

B

32. If a motor vehicle increases its speed by 4 km/h each second, its acceleration is a) 4 km/h. b) 4 km/h per second. c) 4 m/s per second. d) 4 m/s

B

33. The average speed of a horse that gallops a distance of 10 km in a time of 30 min is A) 10 km/h. B) 20 km/h. C) 30 km/h. D) more than 30 km/h

B

37. At the end of 1/2 second an apple freely falling from rest has a speed of A) 1 m/s. B) 5 m/s. C) 10 m/s. D) more than 10 m/s.

B

39. When a ball is tossed straight upward, the direction of its acceleration is a) upward also. b) downward, toward Earth's center. c) actually horizontal. d) at some sort of a strange angle.

B

42. If a freely-falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s2, then its speed reading would increase each second by A) 10 m/s. B) 20 m/s. C) 30 m/s. D) 40 m/s. E) depends on its initial speed

B

A 1-kg ball has twice as much speed as a 10-kg ball. Compared with the 1-kg ball, the 10-kg ball has a) the same momentum. b) 5 times as much momentum. c) 10 times as much momentum. d) 100 times as much momentum

B

A 10-kg block is pushed across a friction-free horizontal surface with a horizontal force of 20 N. The acceleration of the block is A) 1 m/s2. B) 2 m/s2. C) 5 m/s2. D) 10 m/s

B

A car pulling a trailer accelerates when the gas pedal is pushed to the floor. If the trailer becomes disconnected, the acceleration of the car will a) decrease. b) increase. c) remain the same. d) None of the above.

B

A martial arts person breaks a board with a blow of 3000 N. The force that acts on the hand is A) less than 3000 N. B) 3000 N. C) more than 3000 N. D) not enough information

B

A push on a 1-kg brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kg brick requires the force to be A) just as much. B) 10 times as much. C) 100 times as much. D) one-tenth as much.

B

Gailileo's demonstration at the Leaning Tower of Pisa.. a) confirmed Aristotle's teachings b)refused Aristotle's teachings c)failed in their purpose d)none of the above

B

Galileo said that if you rolled a ball along a level surface it would A) slow down due to its natural tendency to come to rest. B) keep rolling without slowing down if no friction acted upon it. C) roll as long as its inertia nudged it along. D) eventually roll in the opposite direction

B

If an object's mass is decreasing while a constant force is applied to the object, the acceleration A) decreases. B) increases. C) remains the same.

B

Lillian pulls on a 10-kg wagon with a constant force of 30 N. What is the wagon's acceleration? A) 0.3 m/s2 B) 3.0 m/s2 C) 10 m/s2 D) 30 m/s2

B

The acceleration due to gravity is lower on the Moon than on Earth. Which of the following is true about the mass and weight of an astronaut on the Moon's surface, compared to Earth? A) Mass is less, weight is same. B) Mass is same, weight is less. C) Both mass and weight are less. D) Both mass and weight are the same

B

To steadily (constantly) increase the velocity of something requires a A) steadily increasing force. B) constant net force. C) decreasing force. D) none of the above

B

When a falling object has reached its terminal velocity, its acceleration is A) constant. B) zero. C) g

B

When dishes remain on a table when you yank the tablecloth beneath them, you're demonstrating A) friction. B) inertia. C) constant motion

B

When you ride your scooter you have momentum. When you ride twice as fast you have A) almost twice the momentum. B) twice the momentum. C) four times the momentum. D) none of the above

B

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the rock tends at first to A) continue in a circular path. B) follow a straight-line path. C) spiral inward. D) fall straight downward.

B

You drive your car along the highway at a constant 60 km/h and apply the brakes until the car slows to 40 km/h. If at that moment you suddenly release the brakes, the car tends to A) momentarily regain its higher initial speed. B) continue moving at 40 km/h. C) decrease in speed if no other forces act.

B

Your weight is A) another word for your mass. B) the gravitational attraction between you and Earth. C) a property of mechanical equilibrium. D) the same in all locations

B

13. A 50-N object falling in air experiences 30 N of air resistance. The net force on the falling object is A) 0 N. B) 20 N. C) 50 N. D) 80 N.

B.

14. Given that two forces of 10 N and 15 N act horizontally on an object, the net force must A) be 5 N. B) be 25 N. C) be either 5 N or 25 N. D) lie between 0 N and 25 N.

C

16. The equilibrium rule ΣF = 0 applies to A) objects or systems at rest. B) objects or systems in uniform motion in a straight line. C) both of the above D) neither of the above

C

21. Daisy weighs 120 N and carries Trixie who weighs 40 N on her back. The support force on Daisy's feet is A) 40 N. B) 120 N. C) 160 N. D) more than 160 N.

C

24. A 3000-N bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is A) 30 N. B) 300 N. C) 3000 N. D) more than 3000 N.

C

26. Marie pushes horizontally on her desk, but not hard enough to get it moving. The friction force acting on the desk is A) zero. B) equal to the weight of the desk. C) equal and opposite to her push. D) none of the above

C

31. The average speed of Daisy running a distance of 2 km in a time of one-half hour is A) 1 km/h. B) 2 km/h. C) 4 km/h. D) more than 4 km/h.

C

38. After being dropped from the top of a high building, a free-falling object has a speed of 30 m/s at one instant. Exactly 1 second earlier, its speed was a) the same. b) 10 m/s. c) 20 m/s. d) 40 m/s

C

41. If you toss a ball straight upward at 40 m/s, with no air resistance it returns to you at a speed of A) zero. B) 10 m/s. C) 40 m/s. D) more than 40 m/s.

C

43. Phil Physiker standing at the edge of a cliff throws one ball straight up and another ball straight down, both with the same speed. Both balls hit the ground at A) different speeds. B) the same speed in the same time. C) the same speed in different times. D) none of the above

C

44. When a cat walks across the lawn, its feet push backward on the lawn and A) also push the lawn forward. B) the lawn also pushes backward on its feet. C) the lawn pushes forward on its feet. D) none of the above.

C

7. Compared with the mass of an apple on Earth, the mass of the same apple on the Moon is A) less. B) more. C) the same.

C

A 1-kg block of iron weighs about A) 1 N. B) 5 N. C) 10 N. D) more than 10 N

C

A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10kg brick is A) the same as that of the 1-kg book. B) 5 times as much as for the 1-kg book. C) 10 times as much as for the 1-kg book. D) zero.

C

A 100-kg vehicle accelerates at 1 m/s2 when the net force on it is a) 1 N. b) 10 N. c) 100 N. d) 1000 N.

C

A car traveling at 100 km/h strikes an unfortunate bug that splatters on the windshield. The force of impact is greater on the A) bug. B) car. C) same for both

C

A commercial jet has a mass of 5000 kg. During takeoff the thrust of its engine is 10,000 N, producing an acceleration of A) 0.5 m/s2. B) 1 m/s2. C) 2 m/s2. D) 4 m/s2.

C

A force of 1 N accelerates a 1-kg mass at 1 m/s2. The acceleration of a 2-kg mass acted upon by a force of 2 N is A) half as much. B) twice as much. C) the same. D) none of the above

C

A particle is being accelerated through space by a 10-N force. Suddenly the particle encounters a second force of 10 N in the opposite direction. The particle with both forces acting A) is brought to a rapid halt. B) decelerates gradually to a halt. C) continues at the same speed it had before encountering the second force. D) theoretically tends to accelerate toward the speed of light.

C

An iron ball and wooden ball of the same size are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater A) speed. B) acceleration. C) momentum. D) all of the above

C

Arnold Strongman and little Nellie Newton have a tug-of-war. The greatest force on the rope is provided by a) Arnold, of course. b) Nelie, surprisingly. c) Both the same, interestingly enough. d) None of the above.

C

Earth moves about 30 km/s relative to the Sun. When you jump upward in front of a wall, the wall doesn't slam into you at 30 km/s because the wall A) has too little gravity to influence you. B) moves in the opposite direction to you. C) and you move at the same horizontal speed, before, during, and after your jump. D) has negligible inertia compared with the Sun

C

If a non-rotating object has no acceleration, then we can say for certain that it is A) at rest. B) moving at constant non-zero velocity. C) in mechanical equilibrium. D) all of the above E) none of the above

C

If you blow up a balloon, and then release it, the balloon will fly away. This is an illustration of A) Newton's first law. B) Newton's second law. C) Newton's third law. D) Galileo's law of inertia.

C

The attraction of a person's body toward Earth is called weight. The reaction to this force is A) the person's body pushing against Earth's surface. B) Earth's surface pushing against the person's body. C) the person's body pulling on Earth. D) none of the above

C

What is the speed of a 6-kg ball with a momentum of 72 kg∙m/s? A) 3 m/s B) 4 m/s C) 12 m/s D) 48 m/s

C

When a rocket ship gaining speed in remote, gravity-free outer space runs out of fuel, it A) gains speed for a short time, then slows down to a constant velocity. B) gains speed for a short time, slows down, and eventually stops. C) no longer gains speed. D) comes to a quick stop

C

When an apple that weighs 1 N is dropped and freely falls, the net force on the apple is A) 0 N. B) 0.1 N. C) 1 N. D) 10 N

C

Which has the greater momentum when moving? A) a container ship B) a bullet C) either of these depending on speed

C

You cannot exert a force on a wall A) if the wall resists. B) unless you put your mind to it. C) unless the wall simultaneously exerts the same amount of force on you.

C

25. The force of friction between materials sliding against each other depends on a) the kind of materials. b) the roughness of the materials. c) the force with which they are pressed together. d) All of the above

D

29. A mosquito flying at 3 m/s encounters a 3-m/s breeze blowing in the same direction, which gives it a resulting speed over the ground of A) 0 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s

D

30. While in an airplane flying at 100 km/h you look down from the window and spot another airplane flying at the same speed in the opposite direction. Relative to you, the speed of the spotted plane is A) zero. B) 100 km/h. C) 150 km/h. D) 200 km/h.

D

34. A body undergoes acceleration whenever there is a change in its a) speed. b) velocity. c) direction. d) All of the above.

D

35. The acceleration of a Tesla that maintains a constant velocity of 120 km/h over a time of one-half hour is A) 60 km/h. B) 120 km/h. C) 240 km/h. D) zero because of no change in velocity.

D

45. Consider a ball that picks up a speed of 3 m/s each second when it rolls from rest down an inclined plane. If the ball takes 4 seconds to reach the bottom, its speed at the bottom will be A) 3 m/s. B) 10 m/s. C) 5 m/s. D) 12 m/s

D

A 1-kg ball is thrown straight up at 10 m/s. Neglecting air resistance, the net force that acts on the ball when it is halfway to the top of its path is A) 1/2 N. B) 1 N. C) 5 N. D) 10 N

D

A 10-kg mass at Earth's surface weighs about A) 1 N. B) 5 N. C) 10 N. D) 100 N. E) 1000 N

D

A heavy rock and a light rock in free fall have the same acceleration because the A) force due to gravity is the same on each. B) air resistance is always zero in free fall. C) inertia of each is the same. D) ratio of force to mass is the same.

D

A skydiver who weighs 500 N reaches terminal velocity at 90 km/h. The air resistance on the skydiver is A) 90 N. B) 250 N. C) 410 N. D) 500 N

D

After a ball tossed upward leaves your hand, the force of gravity on it A) no longer acts. B) gradually diminishes. C) gradually increases. D) remains constant

D

As a flying squirrel falls faster and faster through the air, a) air resistance increases. b) net force decreases. c) acceleration decreases. d) All of the abov

D

Compared with a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much A) inertia. B) mass. C) volume. D) all of the above E) none of the above

D

The change in momentum of an object is equal to the A) force acting on it. B) change in its velocity. C) object's mass times the force acting on it. D) impulse that acts on it

D

The force exerted on the tires of a car to directly accelerate the car along a road is exerted by the A) engine. B) tires. C) air. D) road

D

What applied horizontal force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight? A) 600 N B) 1600 N C) 2000 N D) 2400 N

D

When a 10-kg block is simultaneously pushed eastward with 20 N and westward with 15 N, the net force on the block is a) 35 N west. b) 35 N east. c) 5 N west d) 5 N east.

D

When a 500-N parachutist opens his chute and experiences 800 N of air resistance, the net force on him is A) 300 N downward. B) 500 N downward. C) 800 N downward. D) 300 N upward.

D

Your friend says that impulse equals momentum. This statement isn't correct, and the missing word is a) work. b) acceleration. c) speed or velocity. d) change.

D