Choose the correct option for each question. There is only one correct response for each question.
Which of these sentences is correct?

Options

A. Frictional force is always equal in magnitude and in the same direction to the applied force.
B. Frictional force can act only when two surfaces are in contact with each other.
C. Frictional force exists only between solid surfaces
D. Frictional force decreases with increase in mass.

Answer

B