Friction in 8th Class

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

Distance between the surfaces

Temperature of the surfaces

Color of the surfaces

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

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.

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.

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.

Pushing a heavy box on the floor

Sitting on a chair

Riding a bike on a smooth road

Sliding on ice

Friction force = coefficient of friction x normal force

Friction force = force x velocity

Friction force = distance / time

Friction force = mass x acceleration

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.

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.

Sliding friction and rolling friction

Static friction and magnetic friction

Fluid friction and air friction

Rolling friction and static friction