Two crates, of mass 75 kg and 110 kg, are in contact and at rest on a horizontal surface. A 620-N force is exerted on the 75-kg 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.

Question

(c) Repeat with the crates reversed.

the boxes are horizontally aligned on a flat surface.

please help me... I don't get this problem:(

Answer 1

well push on the 75 and the 75 pushes on the 110
sum is 185 kg and it all accelerates at a
push force = p
p - 75 g*.15 - 110 g*.15 = 185 a
if g = 9.8
620 - 185 g*.15= 185 a
620 - 271= 185 a
a = 1.88 m/s^2

now the second one is accelerated at 1.88 m/s^2
so
Fbetween - m g*.15 = 1.88 m
Fbetween = m (1.88 + 1.47) = 3.35 m for either m

Answer 2

Tf did 1.47 come from