"A proton has an initial speed of 4.9×105 m/s . Part A What potential difference is required to bring the proton to rest? Express your answer using two significant figures."

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 10.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.90 m/s; (b) he is then lifted at the constant speed of 4.90 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 68.0 kg rescue by the force lifting him during each stage?

=force × distance a. work b. velocity c. pressure d. momentum

If the force applied to an object remains constant, is more power needed for the object to move faster ? explain