840 inches to cm show work pls

When an object moves in uniform circular motion, the direction of its acceleration is a) in the same direction as its velocity vector. b) in the opposite direction of its velocity vector c) is directed toward the center of its circular path. d) is directed away from the center of its circular path. e) depends on the speed of the object.

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

Name three different units of energy used to measure heat and describe what type of situations each is usually used.