Question

What is the difference of force of friction acting on a body moving on a fixed surface?

• A. Along the different of motion
• B. Opposite to the direction of motion
• C. Independent of Motion
• D. Both (A) and (B)

Answer 1

The correct option is B Opposite to the direction of motion

When we try to slide a body on a surface, the motion of the body is opposed by a force called the force of friction. The frictional force arises due to intermolecular interaction.

When an external force $\left(F\right)$ is applied to move the body and the body does not move, then the frictional force acts opposite to applied force $F$ and is equal to the applied force i.e., $F-f=0$ frictional force ,$f$ and applied force $F$ . When the body remains at rest, the frictional force is called the static friction. Static friction is a self-adjusting force.

Friction force, $f_r=\mu mg$

Where,

$\mu$ = coefficient of friction.

Hence, friction force act opposite to the direction of motion.