A brick slides on a horizontal surface.Which of the following will increase the frictional force on it?
A)Putting a second brick on top
B)Decreasing the surface area of contact
C)Increasing the surface area of contact
D)Decreasing the mass of the brick
E)None of the above

Question

Quizplus · Accepted Answer

The frictional force between two surfaces is directly proportional to the normal force acting on them. By putting a second brick on top, the normal force (due to the weight of the bricks) increases, thereby increasing the frictional force.

A Brick Slides on a Horizontal Surface