Physics chapter 4

Which of the following statements describe free-body diagrams? I. Force diagrams show force vectors as arrows. II. Forces exerted on the object are represented. III. Forces exerted by the object are represented. A I and II B I and III C II and III D I, II, and III

A I and II

Which of the following is true of inertia? A It is described in Newton's first law of motion. B It is a property of motion. C It is measured by weight. D all of the above

A It is described in Newton's first law of motion.

In interactions of action-reaction pairs involving Earth and everyday objects, the effect on Earth's motion is often negligible because A field forces do not obey Newton's third law. B Earth has great inertia. C everyday objects cannot exert forces on Earth. D all of the above

B Earth has great inertia.

A plank is inclined at angle , north of west. The direction of the normal force exerted by that plank on an object would be oriented at angle , A north of west. B east of north. C south of east. D west of south.

B east of north.

A student holds a 6-N block of wood from a spring balance in an express elevator that maintains constant velocity traveling between floors. A spring scale reading of 5.9 N indicates that the elevator is A starting an ascending trip. B ending an ascending trip. C ending a descending trip. D traveling between floors

B ending an ascending trip.

An action exerted on an object which may change the object's state of rest or motion defines A acceleration. B force. C mass. D velocity.

B force.

Units that measure weight are units of A acceleration. B force. C mass. D velocity.

B force.

For an object in contact with a given surface, the kinetic friction acting on the object A usually is more than static friction. B is independent of the normal force. C depends on the composition and qualities of the surfaces in contact. D acts perpendicular to the surface.

C depends on the composition and qualities of the surfaces in contact.

The gravitational force exerted on an object would most likely be represented by which force vector? A ^ B > C v D <

C v

Which of the following situations describes inertia? A A stationary object tends to resist being moved. B A moving object tends to resist a change in speed. C A moving object tends to resist a change in direction. D all of the above

D all of the above

Two forces act on an object. The magnitude of the net force acting on the object A equals the sum of the magnitudes of the two forces. B equals the difference in the magnitudes of the two forces. C equals the average of the two forces. D cannot be determined from the given information.

D cannot be determined from the given information.

The coefficient of kinetic friction A is a type contact force. B is measured in newtons. C depends on the normal force. D depends on the composition and qualities of the surfaces in contact.

D depends on the composition and qualities of the surfaces in contact.

A batter strikes a baseball with a bat. Identify an action-reaction pair and describe the forces exerted by each. A The batter exerts a force on the bat; the ball exerts a force on the bat. B The batter exerts a force on the bat; the bat exerts a force on the batter. C The bat exerts a force on the batter; the bat exerts a force on the ball. D The ball exerts a force on the bat; the bat exerts a force on the batter.

B The batter exerts a force on the bat; the bat exerts a force on the batter.

A lubricant decreases kinetic friction between surfaces. The most likely reason it reduces kinetic friction is because the lubricant A reduces the normal force. B changes the composition and qualities of the surfaces in contact. C increases static friction. D produces greater adhesion between the two surfaces

B changes the composition and qualities of the surfaces in contact.

Two dogs are tugging on a toy. One dog pulls with a horizontal force of 14 N due north. The other is pulling due east with a horizontal force of 14 N. What is the direction of the net external horizontal force on the toy? A north B northeast C west D northwest

B northeast

An object is at rest on an incline. The component of gravity acting downward and along the incline on the object is described as Fg,x = +8.0 N. Which axis is pointing up the incline? A +x-axis B +y-axis C -x-axis D -y-axis

C -x-axis

A truck and a car uniformly accelerate from rest to a velocity of 3.0 m/s in equal time intervals. The truck is ten times as massive as the car. Which of the following statements is correct? A The acceleration of the truck is 1/10 that of the car. B The truck travels 1/10 the distance of the car. C The force on the truck is 10 times the force on the car. D all of the above

C The force on the truck is 10 times the force on the car.

The change in the horizontal velocity of a 12-kg scooter is +0.5 m/s. What is the net horizontal force acting on it? A +24 N B +6.0 N C greater than 0 N D 0 N

C greater than 0 N

A single force acting on an object is represented in a free-body diagram of the object by the following force vector: . Which of the following force vectors represents a single force acting on the object that will bring the object into equilibrium? A ^ B > C v D <

C v

Two books are lying next to each other on a library table. The force due to gravity on the first book is 9 N and on the second is 13 N. The gravitational force on the table itself is 125 N. The floor supports the table with an upward force of 147 N. In a free-body diagram of the table, how many contact forces and how many field forces should be represented? A 1, 2 B 1, 3 C 2, 2 D 3, 1

D 3, 1

A force of 5 N and a force of 15 N acting on an object can produce the following net forces except A 20 N. B 15 N. C 10 N. D 5 N.

D 5 N.

During a three-part circus stunt, a clown holds a ball. The clown then tosses the ball upward. After releasing it, the ball is caught a few moments later from above by another clown on a trapeze. Which set of data could represent the normal force exerted by the ground on the first clown during the stunt? The force due to gravity on the clown is 680 N and that on the ball is 20 N. A 700 N, 695 N, 720 N B 700 N, 695 N, 700 N C 700 N, 705 N, 700 N D 700 N, 705 N, 680 N

D 700 N, 705 N, 680 N

All of the following statements about kinetic friction are true except A Kinetic friction is calculated by the equation Ff = µkFn. B Kinetic friction is exerted parallel to the surface. C Kinetic friction is exerted opposite the direction of motion. D For an object on an incline, kinetic friction increases as the angle of the incline above the horizontal increases.

D For an object on an incline, kinetic friction increases as the angle of the incline above the horizontal increases.

Which of the following statements are true about the concept of field forces? I. Field forces can be exerted by objects that are in physical contact. II. Field forces can be exerted by objects that are not in contact. III. There are four fundamental field forces. A I only B II only C II and III D I, II, and III

D I, II, and III

Which of the following statements describe an object in equilibrium? I. The object is at rest. II. The object is moving at constant velocity. III. The net external force on the object is zero. A I and II B I and III C II and III D I, II, and III

D I, II, and III

Which of the following statements describe force diagrams? I. Force diagrams show force vectors as arrows. II. Forces exerted on the object are represented. III. Forces exerted by the object are represented. A I and II B I and III C II and III D I, II, and III

D I, II, and III

Which of the following statements are true about Fs, max in the equation µs = ? I. Fs, max is exerted perpendicular to the surfaces in contact. II. Fs, max represents the maximum value of the force of static friction. III. On a level surface, the magnitude of Fs, max equals the magnitude of the applied force that starts the object moving. A I only B II only C I, II, and III D II and III

D II and III

In which situation is the net force acting on a car zero? A The car increases speed and changes direction. B The car increases speed but does not change direction. C The car maintains its speed but changes direction. D The car maintains both its speed and direction.

D The car maintains both its speed and direction.

A force unit is defined as the product of a mass unit and a unit of A time. B displacement. C velocity. D acceleration.

D acceleration.

In an action-reaction pair, the A action force is exerted first. B action force and the reaction force are equal in magnitude and act in the same direction. C action force and the reaction force are contact forces only. D action force and the reaction force act on two different objects.

D action force and the reaction force act on two different objects.

The normal force A equals Fg in magnitude. B points vertically upward. C is a scalar quantity. D acts perpendicular to a surface.

D acts perpendicular to a surface.

The acceleration due to gravity A is caused by a field force. B has a magnitude of 9.81 m/s2 at Earth's surface. C is represented by the symbol, ag. D all of the above

D all of the above