posted by dawn on .
A horizontal force of magnitude 22 N is applied to a 3.0 kg book as the book slides a distance d = 0.5 m up a frictionless ramp at angle è = 30°. The book begins with zero kinetic energy. What is its speed at the end of the displacement?
No friction so any work done on it = change in PE + change in KE
Assume both PE and KE are zero at start.
How far up did it go?
h = .5 sin 30 = .25 meters up
How much potential energy did it gain?
PE = m g h = 3.0 * 9.8 * .25 = 7.35 Joules
How much work was done on it
Force in direction of motion = 22 cos 30 = 19.1 N
work done = 19.1 * .5 = 9.53 joules
9.53 = KE + 7.35
(1/2) m v^2 = 2.18 Joules
I think you can get v from there