Friction in Engineering Mechanics: Interactive Learning Quizzes

Question 1

A block slides down an inclined plane with a constant velocity. What is the relationship between the coefficient of kinetic friction between the block and the plane and the angle of inclination?

Accepted Answer

Coefficient of kinetic friction = tan(angle of inclination)

Answer

Coefficient of kinetic friction = sin(angle of inclination)

Answer

Coefficient of kinetic friction = cos(angle of inclination)

Question 2

Which of the following is an example of rolling friction?

Accepted Answer

A wheel rolling on a flat surface

Answer

A block sliding on a flat surface

Answer

A ball bouncing on a floor

Question 3

What is the primary purpose of applying a lubricant between two sliding surfaces?

Accepted Answer

To reduce friction and wear

Answer

To reduce friction and increase wear

Answer

To increase friction and increase wear

Answer

To increase friction and reduce wear

Question 4

What is the key difference between static and kinetic friction?

Accepted Answer

Static friction acts before the motion starts, while kinetic friction acts during the motion.

Answer

Static friction is always greater than kinetic friction.

Answer

Kinetic friction is always greater than static friction.

Question 5

What is the SI unit of coefficient of friction?

Accepted Answer

Dimensionless

Answer

Newton

Answer

Pascal

Answer

Coulomb

Question 6

Which of the following surfaces typically provides the highest coefficient of friction?

Accepted Answer

Rough, dry surface

Answer

Smooth, wet surface

Answer

Smooth, dry surface

Question 7

In a friction clutch, friction is used primarily to:

Accepted Answer

Transmit power between two rotating shafts

Answer

Lubricate the bearings

Answer

Reduce noise and vibrations

Question 8

The angle of repose for a material on a surface is the angle at which:

Accepted Answer

The material begins to slide down the surface due to gravity

Answer

The material rolls down the surface

Answer

The material stops sliding down the surface

Question 9

Coulomb's law of friction states that:

Accepted Answer

The force of friction is directly proportional to the normal force

Answer

The force of friction is independent of the surface area

Answer

Kinetic friction is always greater than static friction

Question 10

In a bearing, friction is reduced by using:

Accepted Answer

Rolling elements

Answer

Sliding surfaces

Answer

Belt drives

Answer

Hydraulic fluids

Question 11

The direction of the force of friction is:

Accepted Answer

Opposite to the direction of impending motion

Answer

Perpendicular to the surface

Answer

Randomly oriented

Answer

Parallel to the surface

Question 12

A block of mass 10 kg rests on a horizontal surface. The coefficient of static friction between the block and the surface is 0.4. What is the minimum horizontal force required to start the block moving?

Accepted Answer

39.2 N

Answer

9.8 N

Answer

19.6 N

Question 13

A box is pulled across a rough floor with a constant velocity. Which statement accurately describes the forces acting on the box?

Accepted Answer

The applied force is equal and opposite to the force of kinetic friction.

Answer

The applied force is less than the force of kinetic friction.

Answer

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

Question 14

A car is braking on a dry road. Which of the following factors will increase the braking force?

Accepted Answer

Increasing the coefficient of friction between the tires and the road.

Answer

Increasing the speed of the car.

Answer

Decreasing the mass of the car.

Question 15

A block is sliding down an inclined plane. The coefficient of kinetic friction between the block and the plane is 0.2. What is the acceleration of the block?

Accepted Answer

The acceleration depends on the angle of inclination.

Answer

9.8 m/s²

Answer

1.96 m/s²

Question 16

A student is pushing a heavy box across a rough floor. They exert a force of 200 N, and the box moves at a constant velocity. What is the force of friction acting on the box?

Accepted Answer

200 N

Answer

300 N

Answer

100 N

Answer

0 N

Question 17

A ball is thrown horizontally off a cliff. Which of the following forces causes the ball to eventually hit the ground?

Accepted Answer

Gravity

Answer

Friction between the ball and the air

Answer

Air resistance

Question 18

A bicycle is rolling down a hill. Which type of friction is primarily responsible for slowing the bicycle down?

Accepted Answer

Rolling friction

Answer

Kinetic friction

Answer

Static friction

Answer

Fluid friction

Question 19

A car is traveling at a constant speed on a horizontal road. The engine is providing a force of 1000 N to overcome friction. What is the total force of friction acting on the car?

Accepted Answer

1000 N

Answer

500 N

Answer

2000 N

Answer

0 N

Question 20

A block of mass 10 kg is resting on a horizontal surface with a coefficient of static friction of 0.4. What is the minimum horizontal force required to start the block moving?

Accepted Answer

39.2 N

Answer

19.6 N

Answer

9.8 N

Answer

49 N

Question 21

A 5 kg box slides down a ramp inclined at 30 degrees to the horizontal. If the coefficient of kinetic friction between the box and the ramp is 0.2, what is the acceleration of the box?

Accepted Answer

2.94 m/s²

Answer

9.8 m/s²

Answer

4.9 m/s²

Answer

1.96 m/s²

Question 22

A car is traveling at a constant speed of 20 m/s. The brakes are applied, and the car comes to a stop after 5 seconds. If the coefficient of kinetic friction between the tires and the road is 0.8, what is the mass of the car?

Accepted Answer

125 kg

Answer

1000 kg

Answer

250 kg

Answer

500 kg

Question 23

Which of the following factors DOES NOT affect the coefficient of friction between two surfaces?

Accepted Answer

The area of contact between the surfaces

Answer

The applied force

Answer

The temperature

Answer

The nature of the surfaces

Question 24

A belt drive system is used to transmit power from a motor to a machine. Which type of friction is primarily responsible for the power transmission?

Accepted Answer

Static friction

Answer

Rolling friction

Answer

Kinetic friction

Question 25

A ball bearing is used to reduce friction in a rotating shaft. What type of friction is primarily reduced by using ball bearings?

Accepted Answer

Rolling friction

Answer

Kinetic friction

Answer

Static friction

Answer

Fluid friction

Question 26

A block is pulled across a rough surface at a constant velocity. Which of the following statements is TRUE?

Accepted Answer

The applied force is equal to the force of friction

Answer

The applied force is less than the force of friction

Answer

The applied force is greater than the force of friction

Question 27

A car is moving at a constant speed on a level road. The engine is providing a forward force of 1000 N. What is the force of friction acting on the car?

Accepted Answer

1000 N

Answer

2000 N

Answer

500 N

Answer

0 N

Question 28

Which of the following statements is NOT true about friction?

Accepted Answer

Friction is always a desirable force

Answer

Friction can be used to generate heat

Answer

Friction can cause wear and tear on surfaces

Answer

Friction can be reduced by using lubricants

Question 29

A brake system in a car uses friction to slow down the vehicle. Which type of friction is primarily responsible for braking?

Accepted Answer

Kinetic friction

Answer

Fluid friction

Answer

Rolling friction

Answer

Static friction

Question 30

Which of the following statements about friction is correct?

Accepted Answer

Friction is a force that opposes the relative motion between two surfaces in contact

Answer

Friction always acts in the direction of motion

Answer

Friction is a conservative force

Question 31

The coefficient of static friction is typically:

Accepted Answer

Greater than the coefficient of kinetic friction

Answer

Independent of the materials in contact

Answer

Equal to the coefficient of kinetic friction

Answer

Less than the coefficient of kinetic friction

Question 32

Which of the following factors does NOT affect the coefficient of friction?

Accepted Answer

Surface roughness

Answer

Materials in contact

Answer

Normal force

Question 33

A block of mass 10 kg is at rest on a horizontal surface. The coefficient of static friction between the block and the surface is 0.5. What is the maximum horizontal force that can be applied to the block without causing it to move?

Accepted Answer

50 N

Answer

400 N

Answer

100 N

Answer

200 N

Question 34

Which of the following statements about kinetic friction is true?

Accepted Answer

Kinetic friction is independent of the velocity of the moving surfaces

Answer

Kinetic friction is always less than static friction

Answer

Kinetic friction acts in the opposite direction to the motion

Question 35

A car is traveling at a speed of 20 m/s on a level road. The coefficient of kinetic friction between the tires and the road is 0.2. What is the distance the car will travel before it comes to a stop?

Accepted Answer

50 m

Answer

400 m

Answer

200 m

Answer

100 m

Question 36

Which of the following devices utilizes friction to function?

Accepted Answer

Brake pads

Answer

Electric motor

Answer

Light switch

Answer

Battery

Question 37

Friction can be reduced by:

Accepted Answer

Using lubricants

Answer

Increasing the temperature

Answer

Increasing the surface roughness

Answer

Decreasing the normal force

Question 38

Rolling friction is typically:

Accepted Answer

Less than sliding friction

Answer

Independent of the radius of the rolling object

Answer

Equal to sliding friction

Answer

Greater than sliding friction

Question 39

Which of the following factors does NOT affect rolling friction?

Accepted Answer

Surface roughness

Answer

Coefficient of friction

Answer

Radius of the rolling object

Answer

Weight of the rolling object