[" A batcely rights a builb.Describe the energy changes involved "],[" in the process."],[" Certain force acting on a "20kg" mass changes its velocity from "],[5ms^(-1)" to "2ms^(-1)" .Calculate the work done by the force."],[" A mass of "10kg" is a point "A" on a table.It is moved to a point "],[B" .If the line joining "A" and "B" is horizontal,what is the verel "]