Question

A bike is moving north when the rider applies the brakes. In which direction does the frictional force act between the ground and the bike's wheels?

A.north
B.south
C.upward
D.downward

Answer 1

Since the biker is moving in the north direction. So, its velocity is in the north direction. Now, when he applies the brake, it slows down due to friction. Since, the velocity is decreasing. Hence, the acceleration direction is in the opposite direction and the direction opposite to the north is south. Hence, the frictional force is acting in the south direction.

So, the answer is B. South