physics----dynamics

1. Two crates of mass 75kg and 110kg are in contact and at rest on a horizontal surface.A 730N force is exerted on the 75 hg crate. If the coefficient of kinetic friction is 0.15, calculate (a) the acceleration of the system and (b) the force that each crate exerts on the other.


2. A wet bar of soap(mass=150 g ) slides without friction down a ramp 2.0m
long inclined at 7.3degree, How long does it take to reach the bottom? Neglect friction. How would this change if the soap's mass were 250 grams?