Conceptual Physics Concept Test Questions Actions and Reactions

Conceptual Physics Concept Test Questions Actions and Reactions The following slides were created through a collaboration of the Industry Initiatives in Science and Math Education (IISME) and Stanford University

A vase of flowers is at rest on a table in a room in a building rooted to the earth. There is no significant air movement. The number of forces acting on the vase is. . a. 0 b. 1 c. 2

The space shuttle is able to lift off the ground because. . a. rocket propulsion is due to exhaust gases that push on something behind the rocket. b. the Earth resists the gases coming out of the back of the rocket. c. the gases coming out of the rocket push back on the rocket. d. the heat from the rocket engine causes hot air to rise, and that rising air lifts the rocket up.

A man is pushing on box 'A'. Which of the following is not true? a. Box A is pushing on box B. b. Box B is pushing on box A. c. Box A is pushing on the man. d. Box B is not doing any pushing. e. b and c.

A man pushes against a wall. Besides his force on the wall, there is a force. . a. from the wall back on the man. b. holding the man back from behind. Otherwise, he would knock the wall over. c. nowhere. Only the man and maybe gravity are exerting forces in this example.

A person pulls a box across the floor. Which is the correct analysis of the situation? 1. The box moves forward because the person pulls forward slightly harder on the box than the box pulls backward on the person. 2. Because action always equals reaction, the person cannot pull the box- the box pulls backward just as hard as the person pulls forward, so there is no motion. 3. The person gets the box to move by giving it a tug during which the force on the box is momentarily greater than the force exerted by the box on the person. 4. The person’s force on the box is as strong as the force of the box on the person, but the frictional force on the person is forward and large while the backward frictional force on the box is small. 5. The person can pull the box forward only if he or she weighs more than the box.

Two men attempt to pull apart a coconut and are unable to do so. If instead, one rope is tied to a very strong tree and both men pull on the other end, the tension on the coconut would be _____ what it was originally. 1. twice 2. exactly the same as 3. half Adapted from Eric Mazur’s Peer Instruction

A horse is pulling a buggy at a constant velocity. Which of the following forces are acting on the buggy? a) The force of the horse b) The force of the reigns c) The force of the horse transmitted through the reins d) All of the above

A ball, attached to a chain, is swung in a circular pattern as depicted to the left. Which of the following forces provides the centripetal acceleration necessary for the ball to remain in a circle? a) Gravity b) The force on the ball by the man c) The force on the ball by the chain d) All of the above

A ball, attached to a chain, is swung in a circular pattern as depicted to the left. The removal of which of the following forces would cause the ball to fly off in a straight line, as shown? a) Gravity b) The force on the chain by the man c) The force on the ball by the chain d) (a) and (b) e) (b) and (c) f) (a) and (c)

Consider a horse standing on the ground. Is the following statement true? The weight of the horse and the normal force exerted by the ground on the horse constitute an action-reaction pair that are always equal and opposite according to Newton’s third law. 1. yes 2. no Adapted from Eric Mazur’s Peer Instruction

Consider a car at rest. We can conclude that the downward gravitational pull of Earth on the car and the upward contact force of Earth on it are equal and opposite because ______ 1. the two forces form an interaction pair. 2. the net force on the car is zero. 3. neither of the above

A skydiver is falling with a constant velocity of 60 ms-1. Choose the correct list of forces acting on the skydiver. a. Gravity down only b. Gravity down and air pushing up c. Gravity down and air pushing down d. There are no forces on this skydiver.

A man is pushing to the right on a box, but it is not moving. Select the choice below that correctly identifies the forces on the box. a. Force of man pushing to the right only. b. Force of man pushing to the right and force of friction to the left. c. Force of man to the right and force of friction to the right. d. Force of friction only. e. There are no forces acting on the cube.

Two identical blocks rest on two identical tables. A pig on a pogo stick is bouncing on block B. Compared to the normal force exerted by the table on block A, the normal force exerted by the table on block B is. . a. the same. b. greater. c. less

A girl is accelerating upward on a diving board. The normal force of the diving board on the girl is. . a. less than the girl's weight. b. equal to the girl's weight. c. more than the girl's weight. d. zero.

A person is standing in an elevator that is accelerating upward. The upward normal force, N, exerted by the elevator floor on the person is ______ the downward weight W of the person. 1. larger than 2. identical to 3. smaller than Acceleratin g Adapted from Eric Mazur’s Peer Instruction

Which of the following statements is not true. a. The woman is pushing up on box B. b. Box B is pushing up on box A. c. Box A is pushing down on box B. d. Box B is pushing down on the woman. e. Box B is not doing any pushing. f. b, c, and d.

Below is a list of possible forces present for the situation of a woman sitting in a chair. 1. Woman's force on chair. 2. Chair's force on woman 3. Chair's force on ground. 4. Ground's force on woman. 5. Woman's force on ground from foot. Which of the above are real forces? a. none b. all c. 1 and 5 d. 1, 4, and 5

Rockets move in space because. . a. the burning gases push on the rocket. b. the burning gases push on whatever is behind the rocket. c. the rocket sucks in and pushes back space gases just like a jet turbine.

This world record land rocket moves forward because. . a. burning gases push on the ground at an angle. b. air is sucked in the front and pushed out the back. c. air and burning gases push forward on the rocket.

A bird at rest on a branch is facing the wind. The wind is constant and the bird is not moving. The number of forces acting on the bird is. . a. 0 b. 1 c. 2 d. 3 e. at least 4

A boy is at rest on a steep hill with his foot on a skateboard. The skateboard is not moving. The number of forces on the skateboard is. . a. 0 b. 1 c. 2 d. 3 e. at least 4

Three objects are in contact as shown on a table surface. Object 2, a woman, slid down the ramp until coming into contact with object 3 and then stopped where she is. There are no other objects on the table. Identify the number of forces acting on object 3 a. 0 b. 1 c. 2 d. 3 e. 4 f. 5

A boy and a dog each have the same mass. The boy rides a skateboard as shown. The dog rides a surfboard as shown. Each moves with constant speed horizontally. Which of the following is true? a. Both the dog and the boy exert force on their boards. b. The boy exerts a force on the skateboard, but the dog exerts no force on the surfboard. c. Neither of them exerts a force on their boards because they are moving horizontally.

Three objects are in contact as shown on a table surface. Object 2 slid down the ramp until coming into contact with object 3 and then stopped where it is. There are no other objects on the table. Identify the number of forces acting on object 3. a. 0 b. 1 c. 2 d. 3 e. 4 f. 5