A rock was dropped off a cliff from rest. It accelerated downward at 9.8m/s2 and it hits the ground 4.6 seconds later. Neglecting air resistance. what is the
rocks velocity when it hits the ground?

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

As a car drives with its tires rolling freely without any slippage, the type of friction acting between the tires and the road is 100) a) static friction. b) kinetic friction. c) a combination of static and kinetic friction. d) neither static nor kinetic friction, but some other type of friction. e) it is impossible to tell what type of friction acts in this situation.

Which of these is constant for all types of electromagnetic radiation in a vacuum? select one: a. wavelength b. frequency c. photon energy d. amplitude e. velocity