3) In the figure, a 900-kg crate is on a rough surface inclined at 30°. A constant external force P=7200 N is applied horizontally to the crate. While this force pushes the crate a distance of 3.0 m up the incline, its velocity changes from 1.2 m/s to 2.3 m/s. P 30° v2 3.0 m (a) Draw a free body diagram for the crate: (b) How much work does friction do during this process? (c) How much work does gravity do during this process? (d) What is the change in the kinetic energy during this process? 5) The potential energy for a certain mass moving in one dimension is given by U(x) (2.0 J/m3r3 - (15 J/m2)x2 + (36 J/m)x - 23 J (a) Find the location(s) where the force F(x) on the mass is zero. (b) Are these stable or unstable equilibria?