Friction: Interactive Learning Quizzes for Engineering Mechanics

Question 1

Which type of friction occurs when two surfaces are in relative motion?

Accepted Answer

Kinetic friction

Answer

Static friction

Answer

Rolling friction

Answer

Sliding friction

Question 2

What is the coefficient of friction?

Accepted Answer

A constant that characterizes the frictional properties of two surfaces in contact

Answer

The force required to overcome friction

Answer

The angle of inclination at which an object begins to slide

Answer

The distance traveled by an object before it stops due to friction

Question 3

Which of the following is NOT a type of fluid friction?

Accepted Answer

Solid friction

Answer

Laminar flow

Answer

Turbulent flow

Answer

Boundary layer flow

Question 4

What is the relationship between the coefficient of friction and the angle of repose?

Accepted Answer

Coefficient of friction = tan(angle of repose)

Answer

Coefficient of friction = sin(angle of repose)

Answer

Coefficient of friction = cos(angle of repose)

Answer

Coefficient of friction = cot(angle of repose)

Question 5

The coefficient of friction is a dimensionless quantity that represents:

Accepted Answer

The ratio of frictional force to normal force

Answer

The ratio of normal force to frictional force

Answer

The angle between the normal force and the frictional force

Answer

The distance over which friction acts

Question 6

A car is traveling on a flat road at a constant speed. What is the net force acting on the car?

Accepted Answer

Zero

Answer

The force of friction

Answer

The force of gravity

Answer

The force of the engine

Question 7

A block slides down an inclined plane. The angle of inclination is increased. What happens to the component of the block's weight acting down the plane?

Accepted Answer

Increases

Answer

Decreases

Answer

Remains constant

Answer

Cannot be determined without more information

Question 8

Friction is a force that:

Accepted Answer

Resists relative movement between two surfaces in contact

Answer

Is always negative

Answer

Only occurs when two surfaces are directly touching

Question 9

The coefficient of static friction is generally:

Accepted Answer

Greater than or equal to the coefficient of sliding friction

Answer

Less than the coefficient of sliding friction

Answer

Equal to the coefficient of sliding friction

Answer

Unrelated to the coefficient of sliding friction

Question 10

Which of the following factors has NO influence on the coefficient of friction?

Accepted Answer

Coefficient of restitution

Answer

Surface roughness

Answer

Temperature

Answer

Normal force

Question 11

Static friction is the force that resists the:

Accepted Answer

Initial movement of a stationary object

Answer

Continued movement of a moving object

Answer

Rotation of an object

Answer

Vibration of an object

Question 12

The direction of the friction force is always:

Accepted Answer

Parallel to the contact surface

Answer

Perpendicular to the contact surface

Answer

At an angle to the contact surface

Answer

Independent of the contact surface

Question 13

Which of the following is an advantage of friction in engineering applications?

Accepted Answer

Prevents slippage

Answer

Generates heat

Answer

Causes wear and tear

Answer

Reduces efficiency

Question 14

A block of mass m is placed on a horizontal surface with coefficient of static friction μs. What is the minimum force required to start moving the block?

Accepted Answer

μs * m * g

Answer

μk * m * g

Answer

m * g

Answer

μk * m

Question 15

A car traveling at a speed v applies brakes. The coefficient of kinetic friction between the tires and the road is μk. What is the stopping distance?

Accepted Answer

v^2 / (2 * μk * g)

Answer

v^2 / (μk * g)

Answer

v / (2 * μk * g)

Answer

v / (μk * g)

Question 16

Which of the following is an example of rolling friction?

Accepted Answer

A car tire rolling on the road

Answer

A block sliding on a surface

Answer

A fluid flowing through a pipe

Answer

A person walking on a sidewalk

Question 17

Which of the following statements best describes the fundamental nature of friction?

Accepted Answer

Friction is a force that opposes the relative motion of two contacting surfaces.

Answer

Friction always acts in the same direction as the applied force.

Answer

Friction is a conservative force.

Answer

The magnitude of friction is unaffected by the normal force between the surfaces.

Question 18

Which factor does not affect the coefficient of friction?

Accepted Answer

Relative humidity

Answer

Surface roughness

Answer

Material properties

Answer

Contact area

Question 19

In a pulley system, the effect of friction is to:

Accepted Answer

Decrease the ideal mechanical advantage

Answer

Increase the ideal mechanical advantage

Answer

Have no effect on the ideal mechanical advantage

Answer

Reverse the direction of the applied force

Question 20

The coefficient of friction between two surfaces is typically:

Accepted Answer

Less than 1

Answer

Equal to 1

Answer

Greater than 1

Answer

Zero

Question 21

The frictional force acting on an object is proportional to:

Accepted Answer

Normal force

Answer

Applied force

Answer

Mass of the object

Answer

Velocity of the object

Question 22

Which of the following statements about friction is true?

Accepted Answer

Friction can be both beneficial and harmful

Answer

Friction always opposes motion

Answer

Friction is always beneficial

Answer

Friction can be eliminated completely

Question 23

Which law of friction states that the force of friction is directly proportional to the normal force acting on the surfaces?

Accepted Answer

Amontons' Law

Answer

Coulomb's Law

Answer

Newton's Law of Universal Gravitation

Answer

Hooke's Law

Question 24

What is the purpose of using lubricants in engineering applications?

Accepted Answer

To reduce friction

Answer

To increase friction

Answer

To eliminate friction

Answer

To change the coefficient of friction

Question 25

Friction can have both beneficial and detrimental effects in engineering applications.

Accepted Answer

True

Answer

False

Question 26

The coefficient of static friction is typically:

Accepted Answer

Greater than the coefficient of kinetic friction

Answer

Less than the coefficient of kinetic friction

Answer

Equal to the coefficient of kinetic friction

Answer

Dependent on the relative velocity of the surfaces in contact

Question 27

A block of mass 10 kg is resting on a horizontal surface with a coefficient of kinetic friction of 0.2. The force required to move the block at a constant velocity is:

Accepted Answer

20 N

Answer

10 N

Answer

50 N

Answer

100 N

Question 28

Friction is a non-conservative force because:

Accepted Answer

It dissipates energy

Answer

It depends on the path taken by the body

Answer

It is a contact force

Answer

It is a non-contact force

Question 29

Which of the following is NOT a type of friction between solid surfaces?

Accepted Answer

Fluid friction

Answer

Static friction

Answer

Kinetic friction

Answer

Rolling friction

Question 30

In a friction drive system, the coefficient of friction is:

Accepted Answer

The ratio of the tangential force to the normal force

Answer

The ratio of the normal force to the tangential force

Answer

The ratio of the torque transmitted to the shaft speed

Answer

The ratio of the input power to the output power

Question 31

The angle of friction is defined as:

Accepted Answer

The angle between the normal force and the friction force

Answer

The angle between the applied force and the resultant force

Answer

The angle between the friction force and the horizontal

Answer

The angle between the normal force and the horizontal

Question 32

In a belt drive system, the coefficient of friction is critical for:

Accepted Answer

Preventing the belt from slipping

Answer

Increasing the power transmitted

Answer

Reducing the wear and tear on the belt

Answer

Improving the efficiency of the system

Question 33

Which type of friction manifests when surfaces are stationary relative to one another?

Accepted Answer

Static friction

Answer

Sliding friction

Answer

Rolling friction

Answer

Fluid friction

Question 34

The coefficient of friction, a dimensionless quantity, represents the ratio of:

Accepted Answer

Friction force to normal force

Answer

Normal force to friction force

Answer

Friction force to contact area

Answer

Contact area to friction force

Question 35

The coefficient of friction between two surfaces, denoted by the Greek letter mu (μ), represents:

Accepted Answer

The ratio of the force required to overcome friction to the normal force acting between the surfaces.

Answer

The distance over which friction acts.

Answer

The force of friction acting on the surfaces.

Question 36

According to Coulomb's law of friction, the force of static friction:

Accepted Answer

Is directly proportional to the normal force acting between the surfaces.

Answer

Is equal to the force of kinetic friction.

Answer

Is independent of the normal force.

Answer

Is inversely proportional to the normal force.

Question 37

A block of mass m is resting on a horizontal surface with a coefficient of static friction μs. If the angle of the surface is gradually increased, the block will start to slide when the angle of inclination reaches:

Accepted Answer

arctan(μs)

Answer

45°

Answer

60°

Answer

90°

Question 38

Consider a heavy object on a rough horizontal surface. The force required to initiate sliding of the object is greater than the force required to maintain it in motion because:

Accepted Answer

The force of static friction is greater than the force of kinetic friction.

Answer

The force of kinetic friction is greater than the force of static friction.

Answer

The force of gravity is greater than the force of friction.

Question 39

Friction has both advantages and disadvantages. Which of the following is an advantage of friction?

Accepted Answer

It enables us to walk, run, and drive vehicles by providing grip.

Answer

It makes it difficult to move heavy objects.

Answer

It wastes energy in engines.

Answer

It causes wear and tear on machinery.

Question 40

A block slides down an inclined plane. Which force directly opposes the block's motion?

Accepted Answer

Frictional force

Answer

Tension force

Answer

Normal force

Answer

Gravitational force

Question 41

A block rests on a rough surface.  As you gradually increase the force pulling the block horizontally, what happens to the friction?

Accepted Answer

Static friction increases until it reaches a maximum value, then the block starts to move and kinetic friction takes over.

Answer

Static friction remains constant, and the block does not move.

Question 42

How does the coefficient of friction between a car's tires and the road change when the road is wet compared to dry?

Accepted Answer

The coefficient of friction is lower on a wet road.

Answer

The coefficient of friction is higher on a wet road.

Answer

The coefficient of friction remains unchanged.

Answer

It cannot be determined without more information.

Question 43

Which of these statements is TRUE about rolling friction?

Accepted Answer

Rolling friction is generally lower than sliding friction.

Answer

Rolling friction is independent of the radius of the rolling object.

Answer

Rolling friction is not affected by surface roughness.

Answer

Rolling friction increases with the speed of the rolling object.

Question 44

What type of energy transformation occurs in a car's brake system?

Accepted Answer

Kinetic energy is converted into thermal energy through friction.

Answer

Kinetic energy is converted into potential energy.

Answer

Kinetic energy is converted into chemical energy.

Answer

Kinetic energy is converted into electrical energy.