Friction in 8th Class

What are the factors that affect friction?

• Nature of surfaces, force pressing the surfaces together, smoothness of surfaces

• Distance between the surfaces

• Temperature of the surfaces

• Color of the surfaces

Define static friction.

• The force that accelerates the motion of an object at rest

• The force that causes an object to move at a constant speed

• The force that opposes the motion of an object in motion

• The force that resists the initial motion of an object at rest

Explain the concept of kinetic friction.

• Kinetic friction is the force that attracts two surfaces towards each other.

• Kinetic friction is the force that causes an object to move faster.

• Kinetic friction is the force that opposes the relative motion of two surfaces in contact when they are moving past each other.

• Kinetic friction is the force that occurs when two surfaces are at rest.

How does the surface roughness affect friction?

• Surface roughness causes the surfaces to repel each other.

• Surface roughness decreases the friction between two surfaces.

• Surface roughness increases the friction between two surfaces.

• Surface roughness has no effect on friction.

What is the role of weight in friction?

• Friction is caused by the speed of an object, not its weight.

• The weight of an object affects the frictional force.

• Friction is only affected by the surface area of an object.

• The weight of an object has no effect on friction.

Give an example of static friction in everyday life.

• Pushing a heavy box on the floor

• Sitting on a chair

• Riding a bike on a smooth road

• Sliding on ice

What is the formula to calculate friction force?

• Friction force = coefficient of friction x normal force

• Friction force = force x velocity

• Friction force = distance / time

• Friction force = mass x acceleration

How does the area of contact affect friction?

• Friction increases with the increase in the area of contact.

• Friction is not affected by the area of contact.

• Friction remains the same regardless of the area of contact.

• Friction decreases with the increase in the area of contact.

Explain the concept of limiting friction.

• Limiting friction is the constant amount of friction that can be generated between two surfaces before motion occurs.

• Limiting friction is the maximum amount of friction that can be generated between two surfaces before motion occurs.

• Limiting friction is the average amount of friction that can be generated between two surfaces before motion occurs.

• Limiting friction is the minimum amount of friction that can be generated between two surfaces before motion occurs.

What are the different types of kinetic friction?

• Sliding friction and rolling friction

• Static friction and magnetic friction

• Fluid friction and air friction

• Rolling friction and static friction