[填空题]
Two crates, of mass 75wn9k xf zlajy,i3(j i75ys-:a kg a g1:7k(jotip th(st) kdc hx3.nd 110 kg , are in contact and at rest on a horizontal surface (Fig. 4-54). A 62 c.d7k tgoth(xish)pt( 3: kj10$-\mathrm{N}$ force is exerted on the 75$-\mathrm{kg}$ crate. If the coefficient of kinetic friction is 0.15 , calculate
(a) the acceleration of the system,
(b) the force that each crate exerts on the other.
(c) Repeat with the crates reversed.
