Find the final velocity of two balls colliding head on if the ball with velocity v2i = −21.4 cm/s has a mass equal to half that of the ball with initial velocity v1i = +27.1 cm/s.

Asimply means that over time there was some sort of change.

What is the function of the commutator in a dc motor? a. to spin the magnet b. to change direct current into alternating current c. to change alternating current into direct current d. to spin the wire coil

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.