A brick is resting on a rough incline as shown in the figure.The friction force acting on the brick,along the incline,is
A) zero.
B) equal to the weight of the brick.
C) greater than the weight of the brick.
D) less than the weight of the brick.

Question

A brick is resting on a rough incline as shown in the figure.The friction force acting on the brick,along the incline,is 
A) zero. 
B) equal to the weight of the brick. 
C) greater than the weight of the brick. 
D) less than the weight of the brick.

Quizplus · Accepted Answer

The friction force acting on the brick is opposing the motion of the brick down the incline. Thus, it is in the opposite direction to the weight of the brick. For the brick to be at rest, the friction force must be equal and opposite to the component of the weight of the brick down the incline. As the friction force is less than the weight of the brick, the correct choice is D, less than the weight of the brick.

A Brick Is Resting on a Rough Incline as Shown