Physics Chapter 4 Test

What are the four fundamental forces?

Electromagnetic force, Gravitational Force, Strong Nuclear Force, and Weak Nuclear Force

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?

Greater than 0 N, we cannot determine it's actual amount with the given information.

What is the SI unit for force?

Newton (N)

What is Newton's first law also called?

The Law of Inertia

A force unit is defined as the product of a mass unit and a unit of...

acceleration

Air resistance is a...

form of friction

The force of gravity, when represented in a force or free body diagram, is always...

Facing straight down

What is terminal speed?

The speed at which an object falling through the air stops going any faster

Is force a vector or scalar quantity?

Vector

The gravitational force exerted on an object would most likely be represented by which force vector?

↓

A lubricant decreases kinetic friction between surfaces. The most likely reason it reduces kinetic friction is because the lubricant...

Changes the composition and qualities of the surfaces in contact

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

In interactions of action-reaction pairs involving Earth and everyday objects, the effect on Earth's motion is often negligible because?

Earth has great inertia.

What are the two kinds of forces?

Field and Contact

Which of the following statement(s) 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.

I and II

The greater the electromagnetic attraction is, the ______ the friction is.

greater

The greater the weight is, the ______ the friction.

greater

Kinetic force is always _____ than the maximum static motion

less

Kinetic friction is always in the opposite direction of...

the direction of motion

What is static friction?

the force that resists the initiation of a sliding motion

A single force acting on an object is represented in a free-body diagram of the object by the following force vector. Which force vector represents a single force acting on the object that will bring the object into equilibrium?

↓

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?

- x axis

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?

3 Contact, 1 Field

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

What is Newton's first law?

An object at rest stays at rest and an object at motion stays in motion unless an outside force acts on the object(s)

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 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

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

All of the following statements about kinetic friction are true except a. Kinetic friction is calculated by the equation Ff=(µk)(Fn). 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.

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.

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. (Ask Mrs Hopper)

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

For an object in contact with a given surface, the kinetic friction acting on the object...?

Depends on composition and qualities of the surfaces in contact.

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...?

Ending an ascending trip (Imagine when your in an elevator and when you stop after going up it feels like your feet want to come off the ground)

If a small sports car head-on with a massive truck, which vehicle experiences the greater impact force? Which vehicle experiences the greater acceleration? Explain your answers.

Equal because you cannot have a net force left over; the car because it's smaller mass means greater acceleration

What are the units that measure weight?

Force

What is an action exerted on an object which may change the object's state of rest or motion defines?

Force

Which of the following statement(s) 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.

I, II, and III

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.

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.

I, II, and III

What is Newton's Third Law?

If two objects interact, the magnitude of the force exerted on the first object by the second object is equal to the magnitude of the force simultaneously exerted on the second object by object one; the forces are in opposite directions TL;DR- For every action, there is an equal and opposite reaction

The normal force is always does what?

It always acts perpendicular to a surface.

The coefficient of kinetic friction depends on what...

It depends on the composition and qualities of the surfaces in contact

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

North of East

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?

Northeast

What is Newton's Second Law?

The acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to the object's mass

A batter strikes a baseball with a bat. What is an example of an action-reaction pair in this situation?

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

The rougher a surface is the ______ the friction.

more

What is kinetic friction?

the force that opposes the movement of two surfaces that are sliding over each other

What is Equilibrium?

the state in which the net force of an object is zero

What is Inertia?

the tendency of an object to resist being moved, or to resist a change in speed or direction if it is already moving