Ch5

D

A 7-N vector at an angle of 45° to the horizontal has a vertical component that is about _______. A. 0N B. 3.5 N C. 7N D. 5N

C

A boxer cannot exert much force on a piece of tissue paper suspended in air because _______. A. the time of the interaction is too brief B. there is little follow-through with the punch C. the tissue paper has too little mass to exert as much force on the boxer's fist D. the tissue lacks enough strength

B

A force pair is created when you push on a large crate that rests on the floor. The crate does not move when pushed. Which free-body diagram correctly represents the forces acting on the crate? (Note: Vectors are not drawn to scale)

B

A force pair is produced when a tennis racket strikes a tennis ball. Which of the following best explains why the tennis ball does not have zero net force acting on it? A. The forces act perpendicular to each other. B. Each half of the force pair acts on a different object. C. The force exerted on the ball is greater than that exerted on the racket. D. The two forces act in the same direction.

D

A small car and a large truck have a head-on collision. Which of the following statements is true? A. Both forces are identical. B. The greater force acts on the truck. C. The greater force acts on the car. D. The magnitudes of both forces are the same.

D

A small insect hits your windshield while you are driving in the highway. How do you compare the magnitude and direction of the force exerted by the car on the insect versus the force of the insect on the car? A. They are opposite and the car exerts a higher force on the bug. B. They are equal and perpendicular to each other. C. They are equal and in the same direction. D. They have the same magnitude and opposite directions.

C

As a boxer hits the bag, the bag hits back at the boxer. Which force happens first? A. The boxer on the bag. B. The bag on the boxer. C. They act at the same time. D. They act on different objects.

B

Can you physically touch a person without that person touching you with the same amount of force? A. Yes, when you touch a person, they touch you back with a force that is slightly less due to friction. B. No, when you touch a person, they must touch you with an equal and opposite force. C. Yes, you can touch a person while they choose to not touch you back. D. Yes, when a heavier person touches a lighter person, the lighter person touches back with less force.

B

Compared to the magnet in the video, the magnet in Part A will hover at a position A. at the same distance above the base. B. farther above the base. C. closer to the base.

A

Consider the video tutorial you just watched. Suppose that we repeat the experiment, but this time we replace the original 56-g magnet with a more powerful magnet of the same mass. With the magnet hovering above the base, what will the scale read? The scale has been zeroed (tared) to subtract the weight of the base. A. 56 g B. Less than 56 g but greater than 0 g C. 0g D. More than 56 g E. -56 g

D

Describe the velocity and acceleration vectors of a projectile that is launched vertically up upon reaching its maximum height. A. The velocity points up and acceleration is zero. B. The velocity and acceleration are both zero. C. The velocity and acceleration both point down. D. The velocity is zero and acceleration points down.

A

Earth pulls down on you with a gravitational force that you call your weight. Do you pull up on Earth with the same amount of force? A. Yes, you pull up on Earth with the same force. B. No, the contact force from the ground cancels the force by you on Earth. C. No, the contact force from the ground cancels the force of Earth on you. D. Earth exerts a much greater force on you than you exert on Earth.

A

Fill in the blanks: Newton's first law is often called the law of ____; Newton's second law is the law of ____; and Newton's third law is the law of ____. A. Inertia, acceleration, action -reaction B. Inertia, net force, friction C. Acceleration, inertia, action -reaction D. Action, inertia, force

A

Force vector components for a sled pulled horizontally by a rope at an upward angle _______. A. are normally at right angles to each other B. add up to 180° C. are always opposite each other D. add up to 90°

D

How does a helicopter get its lifting force? A. The helicopter exerts upward forces on the air; the reaction forces of the air on the helicopter are downward and called lift. B. The helicopter exerts downward forces on the air that are slightly greater than the force of gravity, so it can hover. C. The helicopter exerts a downward force on Earth; the reaction force of Earth on the helicopter is called lift. D. The helicopter exerts downward forces on air; the reaction forces of the air on the helicopter are upward and called lift.

B

How does the distance traveled by the bullet compare with the distance traveled by the rifle in the same time, and why? A. The rifle will travel farther than the bullet because it has a greater magnitude of acceleration. B. The bullet will travel farther than the rifle because it has a greater magnitude of acceleration. C. The bullet will travel the same distance as the rifle because they have equal magnitudes of acceleration.

A

How does the force on the rifle compare with the force on the bullet, and why? A. The magnitude of the force of the rifle is equal to the magnitude of force on the bullet and the forces are in the opposite direction, because for every action there is an equal and opposite reaction. B. The magnitude of the force of the rifle is equal to the magnitude of force on the bullet and both forces are in the same direction, because for every action there is an equal reaction. C. The force on the rifle is less than the force on the bullet because the mass of the rifle is greater. D. The force on the rifle is greater than the force on the bullet because the mass of the rifle is greater.

B

How does the magnitude of acceleration of the rifle compare with the magnitude of acceleration of the bullet, and why? A. The magnitude of acceleration of the rifle is greater than the magnitude of acceleration of the bullet. Even though they experience the same magnitude of force, the mass of the rifle is greater, and so the rifle will experience a greater acceleration than the bullet. B. The acceleration of the rifle is smaller than the acceleration of the bullet. They experience the same magnitude of force, but the mass of the rifle is greater, and so the rifle will experience a smaller acceleration than the bullet. C. The magnitude of acceleration of the rifle is equal to the magnitude of acceleration of the bullet because they experience the same magnitude of force.

B

How many forces are required for an interaction? A. One force, a reaction, is needed for an interaction. B. Two forces, an action and a reaction, are needed for an interaction. C. Two forces, a contact force and a friction force, are needed for an interaction. D. One force, an action, is needed for an interaction.

D

Identify the force that propels a rocket. A. The rocket is propelled because the action force of the rocket on the exhaust gases is less than than the reaction force of the exhaust gasses on the rocket. B. The rocket is propelled by the reaction force of the exhaust gasses bouncing off the air molecules outside the rocket C. The rocket is propelled because the action force of the rocket on the exhaust gases is greater than the reaction force of the exhaust gasses on the rocket. D. The rocket is propelled by the reaction force from the particles accelerated out the rear by an action force from the rocket.

D

In the apple-pulling-the orange sequence in this chapter, what is the force that accelerates the system across the floor? A. The backward pull by the orange B. Internal forces C. The resistance to motion by the orange D. Friction between the apple and the floor

B

The force that propels a rocket is that provided by _______. A. decreased mass B. the expelled gas pushing on the rocket C. ejected fuel D. energetic reactions as the fuel is burned

A

The team to win in a tug-of-war is the team that _______. A. pushes harder on the floor while holding the rope B. pulls with the greater force C. yanks the rope D. has the greatest self confidence

A

The video identifies the force pair produced when an apple falls through the air. Which force belongs in a free-body diagram of the apple? A. force of Earth on apple B. contact force C. normal force D. force of apple on Earth

A

To produce a net force on a system, must there be an externally applied net force? A. Yes, there must be an external net force on the system. B. Yes. To accelerate, the internal reaction forces must be zero. C. No, an internal net force is sufficient. D. No. To accelerate, the internal action forces must not equal the internal reaction forces.

A

What explains the dramatically different magnitudes of accelerations that result when a mosquito collides head on with a moving truck? A. unequal masses of the bus and the mosquito B. unequal forces exerted on the bus and the mosquito C. unequal velocities of the bus and the mosquito D. different directions of motion of the bus and the mosquito

D

What happens to the magnitude of the normal vector on a block resting on an incline when the angle of the incline increases? A. The magnitude is zero. B. The magnitude of the normal vector remains the same. C. The magnitude of the normal vector increases. D. The magnitude of the normal vector decreases.

B

What is meant by the term vector resolution? A. When two vectors are added using the parallelogram law, they are said to experience vector resolution. B. A vector can be broken into two components at right angles that add together to make the original vector. C. When two vectors are subtracted using the parallelogram law, they are said to experience vector resolution. D. When a vector is broken into two components parallel to the vector, it is said to experience vector resolution.

E

What is the direction of the net force acting on the object at position A? A. upward B. downward C. to the left D. to the right E. The net force is zero.

C

What is the direction of the net force acting on the object at position B? A. upward B. downward C. to the left D. to the right E. The net force is zero.

B

What is the direction of the net force acting on the object at position C? A. upward B. downward C. to the left D. to the right E. The net force is zero.

D

What is the force of friction acting on a shoe at rest on an incline compared with the resultant of the vectors mg and N? A. It is equal in magnitude to the resultant and opposite in direction to the normal force. B. It is zero. C. It is equal and in the same direction. D. It is equal and opposite.

A

What specific force is accelerating Nellie (Figure 5.23 in the textbook) down the hill? (assume friction to be neglectable) A. The x-component of the force of gravity B. The y-component of the force of gravity C. Gravity D. Normal force

B

When Monkey Mo dangles by a rope and pulls on his cage, each at different angle from the vertical, the rope tension will be greater than _______.' A. the pull on his cage B. both his weight and the pull on his cage C. The answer cannot be determined. D. his weight

B

When hitting a tennis ball with your racquet, the force on the ball has the same magnitude as the force on the _______. A. racquet, and in the same direction B. racquet C. hand that holds the racquet D. player

A

When you push against a wall, what pushes back? A. The wall pushes back. B. Nothing pushes back. C. Your hand pushes back. D. Your fingers push back.

C

Which of Newton's three laws focuses on interactions? A. Newton's second law B. Newton's zeroth law C. Newton's third law D. Newton's first law

A

Which of the force diagrams in the figure correctly displays all of the horizontal forces exerted on the cart by the surrounding air?

A & D

Which of these situations describe the motion shown in the motion diagram at point A? Choose all that apply.

B & E

Which of these situations describe the motion shown in the motion diagram at point B? Choose all that apply.

G

Which of these situations describe the motion shown in the motion diagram at point C? Choose all that apply.

A & D

While sailing your small boat, the wind fades, and you are stranded in the middle of the lake. You try pushing hard on the mast, to no avail. Why? Check all that apply. A. There are no external forces acting on the system. B. You are not strong enough to move the boat. C. Action/reaction forces cancel out. D. These are internal forces to the system.