Physics Chapter 4

Suppose one's hand exerts a force of 12 N upward on a book weighing 10 N. The reaction to the force of the hand on the book is a force of a. 10 N exerted by the Earth on the book. b. 10 N exerted by the book on the Earth. c. 12 N exerted by the book on the hand. d. 10 N exerted by the book on the hand. e. 2 N exerted by the book on the hand.

c. 12 N exerted by the book on the hand.

According to Newton's First Law a. a force is necessary to maintain motion at constant velocity. b. if an object is at rest it will always stay at rest. c. a force is necessary to cause an object to leave its state of rest. d. once an object is in motion a force cannot change its velocity.

c. a force is necessary to cause an object to leave its state of rest.

A crate is acted upon by a net force of 100 N. An acceleration of 4.0 m/s2 results. The weight of the crate is a. 25 lb. b. 25 N. c. 25 kg. d. 245 N. e. 245 lb.

d. 245 N.

A 10-pound sack of potatoes falls from an airplane. As the velocity of the falling sack increases, so does the air resistance on it. When the air resistance equals 10 pounds, the acceleration of the sack will be a. 100 ft/s2 b. 9.8 m/s. c. 9.8 m/s2. d. zero.

d. zero.

You stand on a scale to measure your weight. The reaction to the force the Earth exerts on you is a. the force the scale exerts on you. b. the force the Earth exerts on the scale. c. the force you exert on the scale. d. the force the scale exerts on the Earth. e. the force you exert on the Earth.

e. the force you exert on the Earth.

It is difficult to stop a car on an icy road surface. It is also difficult to accelerate a car on this same icy road. Which of the follow best explains why that is? a. The motor is too cold to work on ice. b. There is little to no friction between the wheels and the tires. c. There is little to no friction between the the tires and the ground.

C. There is little to no friction between the the tires and the ground.

In this diagram a force acting on a block is shown by the arrow labeled F. The mass of the block is known, as is the size of the force, but the observed acceleration is larger than F/m and so another force must act on the block. In which direction (A, B, C, or D) is this force?

D

Aristotle believed that a force was necessary to keep an object moving. Where, in his view, did this force come from in the case of a ball moving through the air? a.Aristotle believed that Earth's gravity pulled the ball forward when it was thrown. b. Aristotle believed that the air got out of the way of the ball and the lack of air created a vacuum in front of the ball, pulling it forward. c. Aristotle believed that the air rushed around the ball to fill the void of where it had been and this air pushed the ball forward.

c. Aristotle believed that the air rushed around the ball to fill the void of where it had been and this air pushed the ball forward.

The belief that a force is necessary for motion to continue at constant velocity was advanced by a. Newton. b. Galileo c. Aristotle

c. Aristotle.

The gravitational force acting on a lead ball is much larger than that acting on a wooden ball of the same size. Which statement is true about when they are dropped? a. The lead ball's acceleration due to gravity is larger than the wooden ball's. b. The lead ball's acceleration due to gravity is less than the wooden ball's. c. The acceleration due to gravity is the same for both balls.

c. The acceleration due to gravity is the same for both balls.

Two equal forces act on two different objects, one of which has a mass ten times as large as the other. The larger object will have _________ acceleration that the less massive object. a. an equal. b. a greater c. a smaller

c. a smaller

You have three carts connected by strings, as shown in the diagram. Assume their masses M1 , M2 , M3 are different from one another. If the acceleration of M1 is called a1 , the acceleration of M2 is called a2 and the acceleration of M3 is called a3 which of the following correctly states the relative size of each masses acceleration? a. a1 > a2 >a3 b. a1 < a2 <a3 c. a1 = a2 = a3 d. a2 > a1 >a3

c. a1 = a2 = a3

An object moving horizontally across a table is observed to slow down. Which of the following statements is the correct explanation? a. The horizontal forces on the object become smaller as the object slows down. b. The vertical forces on the object become smaller as the object slows down. c. The net force on the object is zero causing it to slow down. d. There is a net backwards horizontal force on the object.

d. There is a net backwards horizontal force on the object.

Two block with the same mass are conected by a string and are pulled across a frictionless surface by a constant force, F , exerted by a string (see diagram). Which of the following statements is correct about what will happen to the boxes? a. they will both move with constant velocity. b. the rightmost box will move with constant velocity while the leftmost box accelerates. c. the leftmost will move with constant velocity while the rightmost box accelerates d. both boxes will accelerate

d. both boxes will accelerate

Suppose that a skydiver wears a specially lubricated suit that reduces air resistance to a small constant force that does not increase as the diver's velocity increases. In this situation which of the following statements is correct? a. the diver's terminal velocity will remain the same as any other skydiver. b. the diver's terminal velocity will be less than any other skydiver. c. the diver's terminal velocity will be more than any other skydiver. d. the diver will no longer experience a terminal velocity.

d. the diver will no longer experience a terminal velocity

Two equal magnitude forces act on a box as shown in the diagram. Which of the following statements is correct? a. the object is accelerating to the right b. the object is accelerating to the left c. the object is accelerating both to the right and to the left. d. the object is not accelerating in the horizontal direction

d. the object is not accelerating in the horizontal direction

A ball hangs at rest from a string attached to the ceiling. The string pulls up on the ball with a force equal to its weight. The reaction to the upward force of the string on the ball is a ___________ (direction) force exerted by the __________ on the _______________.

downward, ball, string

A car rounds a curve while maintaining constant speed. Which of the statements is correct? a. The acceleration of the car is zero b. No net force acts on the car c. The velocity of the car is zero d. The velocity of the car is constant e. A net force acts upon the car

e. A net force acts upon the car

A block, moving on a frictionless horizontal surface on Earth, requires a force if it is to be stopped. Now suppose that the same block, moving with the same speed on a frictionless horizontal surface on the Moon, where gravity is less, is to be stopped in the same time. We can say that, compared to the Earth, a. less force is required to stop the block on the Moon. b. the force required would be the same. c. greater force is required to stop the block on the Moon. d. the block could not be stopped.

b. the force required would be the same.

A physics professor places a soda pop can on the table and asks a student to identify the forces acting upon the can and the directions of each force. The two forces acting on the soda pop can are a. the weight force downward and normal force from the table downward. b. the weight force downward and normal force from the table upward. c. the weight force upward and normal force from the table downward. d. the weight force upward and normal force from the table upward.

b. the weight force downward and normal force from the table upward.

How is the mass of an object different from its weight? a. They are not different, they mean the same thing. b. The mass of an object is the amount of force exerted on the object by gravity while the weight is the amount of matter in the object. c. The weight of an object is the amount of force exerted on the object by gravity while the mass is the amount of matter in the object.

c. The weight of an object is the amount of force exerted on the object by gravity while the mass is the amount of matter in the object.

The frictional force, due to air resistance, acting on an object is always a. greater than the net force. b. in the direction of the object's motion. c. in the opposite direction to the object's motion. d. in the upward direction. e. smaller than object's weight.

c. in the opposite direction to the object's motion.

Two blocks of different mass are connected by a string. The system is accelerated across a smooth horizontal surface by a force supplied by a rubber band connected to the less massive block. The tension in the connecting string will be a. greater than the force pulling the leading block. b. the same as the force pulling the leading block. c. less than the force pulling the leading block. d. zero.

c. less than the force pulling the leading block.

You are in an elevator on the top floor of a large building when the elevator begins to accelerate downwards. In this scenario, the normal force on your feet will be. a. greater than the weight force b. equal in magnitude to the weight force. c. less than the weight force.

c. less than the weight force

What are the possible states of motion for the object pictured in the diagram, given the fact that the two forces acting on it are equal and opposite in direction? a. the object must be moving at a constant velocity since there are some forces on it. b. the object cannot be moving since the forces are equal and opposite. c. the object can be moving at a constant velocity or be at rest. d. the object must be moving and accelerating since there are some forces on it.

c. the object can be moving at a constant velocity or be at rest

How did Aristotle explain the continued motion of a thrown object? a.Aristotle believed that an object in motion continues in motion unless stopped. b. Aristotle believed that thrown objects were not touching the Earth and so were not subject to the laws of physics. c. Aristotle believed that the reaction force of the ball acting on the air pushed the ball forward d. Aristotle believed that the air rushed to fill the void left by the moving ball and in doing so pushed the ball

d. Aristotle believed that the air rushed to fill the void left by the moving ball and in doing so pushed the ball

A shiny, spherical, metal alien jumps out of a perfectly good airplane and skydives for a few seconds. Its photographic friend snaps photos of the sphere with a special camera that also captures the forces on the object. This diagram shows a few of the snapshots, but they are out of order. Place them in order, from the instant it jumps out of the plane and begins free-fall until the time it attains terminal velocity. Assume that the parachute has not deployed yet. If any of the diagrams depict a situation not physically possible, omit it from the ordering. a. L, Y, J, Q b. J, Y, L, J c. L, Q, J d. Q, Y e. L, J, Q

e. L, J, Q

The acceleration due to gravity on the moon is approximately one-sixth the gravitational acceleration near the Earth's surface. If a rock is transported from the Earth to the moon which of the following will occur? a. The mass of the rock will increase as will its weight. b. The mass of the rock will decrease as will its weight. c. The mass of the rock will remain the same as will its weight. d. The mass of the rock will remain the same while its weight will increase. e. The mass of the rock will remain the same while its weight will decrease.

e. The mass of the rock will remain the same while its weight will decrease.

How are Newton's first two laws of motion related to each other? a. They are completely independent since the first is for objects without any acceleration and the second is about objects with an acceleration. b. They are completely independent since the first is about objects moving with constant velocity and the second is for objects accelerating. c. They are completely independent since the first is about objects at rest and the second is about objects accelerating. d. They are related to each other since forces are everywhere. e. They are related to each other since the first law is a special case of the second law

e. They are related to each other since the first law is a special case of the second law

What is the direction of the net force acting on the ball?

none, the net force equals zero

What forces act on the ball?

the weight force and the tension force

Two block with the same mass are conected by a string and are pulled across a frictionless surface by a constant force, F , exerted by a string (see diagram). The tension in the string connecting the boxes will be ____ the tension of the string exerting the force, F. a. greater than b. less than c. equal to

b. less than

The basic unit of mass is the _____

Kilogram

A woman weighs 176 lb and another woman weighs 722 N. The woman weighing 176 lb has the greater mass. T/F

True

A toypowered tractor pushes a book across a table to the right.

Which of the following is the correct free-body diagram for the book?

A succinct statement of Newton's Third Law in three words is _____

action equals reaction

A light body and a heavy body are both given identical accelerations. The body acted upon by the larger force is the ________________ body.

Heavy

Your weight is 120 lb. Suppose you are standing on a scale in an elevator moving up with a constant speed of 4 m/s. What would be the reading on the scale? a. 480 lb. b. 120 lb. c. 70 lb. d. 30 lb e. 0

b. 120 lb

A car goes around a curve traveling at constant speed. Which of the following statements is correct? Check all that apply a. The acceleration of the car is zero. b.The net force on the car is zero. c.The net force on the car is not zero. d.The acceleration of the car is not zero.

C and D are correct

The physical quantity that is the measure of inertia is the _____

Mass

Is mass a force? Y/N

No

The normal upward force exerted by the floor on a chair is equal in size but opposite in direction to the weight of the chair. Is this equality an illustration of Newton's third law of motion? Y/N

No

The force of the floor pushing up on you to counter your weight is an example of a ________ force.

Normal

Your mass is 50 kg. Suppose you are standing on a scale in an elevator that starts moving up and increases its speed at the rate of 3 m/s every second. What would be the reading on the scale? a. 740 N b. 640 N c. 340 N d. 0 N

b. 640 N

A common experience is to find that a steady pull is required to keep an object moving, even on a level surface, when friction is present. Analyzing this experience in light of the laws of motion, the accepted conclusion is that a. the laws of motion do not apply where there is friction. b. a frictional force exactly opposes your pull and the first law applies. c. the object is really accelerating but it is not apparent. d. your pull is canceled by the third law reaction force. e. the laws of motion only apply when you start pulling or stop.

b. a frictional force exactly opposes your pull and the first law applies.

Did Galileo's work on motion precede in the time that of Aristotle or Newton? A. it preceded Aristotle B. it preceded Aristotle

b. it preceded Newton

A mule is attempting to move a cart loaded with rocks. Since the cart pulls back on the mule with a force equal in size to the force that the mule exerts on the cart (according to Newton's third law), is it possible for the mule to accelerate the cart? Y/N

Yes

Why did Aristotle believe that heavier objects fall faster than lighter objects? A.Aristotle believed that heavier objects felt a larger force and a larger force made the object move faster. B. Aristotle believed that heavier objects moved the air around them faster and thus produced a larger force and large velocity C. Aristotle conducted many experiments and came to his conclusion after examining his data

a. Aristotle believed that heavier objects felt a larger force and a larger force made the object move faster.

You have three carts connected by strings, as shown in diagram. Assume their masses are such that M1 > M2 > M3 . If a force, F, is applied to M1 and the net force on M2 is called F2 and the net force on M3 is called F3 , which of the following correctly states the relative size of each force? a. F > F2 > F3 b. F < F2 < F3 c. F2 < F < F3 d. F2 > F > F3 e. F2 = F = F3

a. F > F2 > F3

The starship Enterprise locks onto an alien ship (whose mass is much greater than the Enterprise's mass) with its tractor beam (think of this as a futuristic rope) and starts to pull the alien ship toward it. Neither ship has its propulsion engines running. Which ship has greater acceleration towards the other? a. The Enterprise b. The alien ship c. They both move with equal acceleration d. Neither ship can move because there is no friction in outer space.

a. The Enterprise

A boy stits at rest on the floor. Which of the following statements are true? Check all that apply.

a. The boy experiences an upward normal force. b.The boy experiences a downward weight force.

Consider two blocks, one made of wood and the other of lead. They have the same dimensions but the lead is much more massive. If they are dropped and fall long enough to reach terminal velocity, which block experiences a larger force from air resistance? a. The lead block b. The wood block c. The force on each is equal d. It isn't important because air resistance can be ignored

a. The lead block

Two identical cans, one filled with lead shot and the other with feathers, are dropped from the same height by a student standing on the chair. Check all that apply.

a. The lead-shot-filled can experiences the greater force due to gravity b. Both cans experience the same acceleration due to gravity.

The force that accelerates a car on a level road is exerted by the a. road on the tires. b. gears on the axle. c. tires on the road. d. engine on the gears.

a. road on the tires.

The tablecloth trick is where a tablecloth is rapidly pulled out from under some dinnerware without disturbing the dinnerware appreciably. The dinnerware does move a small amount though. Which of the following explanations is correct for this situation? a. the force of friction from the moving tablecloth only acts for a short time b. the force of friction from the moving tablecloth is very large. c. The normal force from the moving tablecloth on the dinnerware becomes very small.

a. the force of friction from the moving tablecloth only acts for a short time