11. Which of the following forces is a contact force? *

A. Gravity

B. Friction

C. Magnetism

D. Electricity

B

Explanation:

Gravity is an invisible force, and so is magnetism and electricity. Friction involves the rubbing of things together to create energy.

B

Explanation:

Friction is the force that you feel whenever you try to drag an object across a surface. Like a box along the floor, or your hand across a counter-top. It requires two objects to be in direct contact with each other (don't worry about air friction AKA "drag").