If the acceleration of an object is zero at some instant in time, what can be said about its velocity at that time? 1. it is negative. 2. it is positive. 3. it is not changing at that time. 4. unable to determine. 5. it is zero.

Coal contains energy. a. light b. kinetic c. chemical d. mechanical

The amount of work done is determined by 2 factors. describe an example of work (using the scientific definition) list the 2 factors that determine the amount of work done.

Engines for propeller-driven aircraft are limited in their maximum rotational speed by the fact that the tip speed of the propeller must not approach the speed of sound in air (mach i). taking 6 ft as a typical diameter for a propeller of a light airplane and 1100 fils as the speed of sound, find the upper limit on the rpm (revolutions per minute) of the propeller shaft.