Question

A brick slides on a horizontal surface. Which of the following will increase the frictional force on it?

1) Increasing the weight of the brick
2) Decreasing the weight of the brick
3) Increasing the surface area of contact between the brick and the surface
4) Decreasing the surface area of contact between the brick and the surface

Answer 1

Increasing the weight of the brick and increasing the surface area of contact between the brick and the surface will increase the frictional force.

Step-by-step explanation:

The frictional force on a sliding brick can be increased by:

1. Increasing the weight of the brick: Frictional force is directly proportional to the normal force, which is the weight of the object pressing down on the surface. Therefore, increasing the weight of the brick will increase the frictional force.
2. Increasing the surface area of contact between the brick and the surface: Frictional force is also directly proportional to the surface area of contact. So, increasing the surface area of contact between the brick and the surface will increase the frictional force.

Conversely, decreasing the weight of the brick or decreasing the surface area of contact will decrease the frictional force.