Physics Newton's Third Law question?

Question

1. The lower block which is 2kg is pulled on by a rope with a tension force of 20N. the coefficient of kinetic friction between the lower block and the surface is 0.30. the coefficient of kinetic friction between the lower block and the upper block(1kg) is also 0.30. What is the acceleration of the 2.0kg block?


2. Find an expression for the acceleration of m1. Assume the table is frictionlesss.
m1 is a box on a surface being pulled by a pulley toward -->
m2 is a dangling box.

show your solution on any question u know please. second question is a bit unclear because i cant post a picture. i'm stuck on these, help please!!

Answer 1

1.
Total force equal to applied force less force of riction between the lower surface
Ft=F-f
(m1+m2)a=u(m1+m2)g
so
a= ( u(m1+m2)g/m1+m2)

force exerted by lower block on upper block
F2=m2 a while
f2=um2g
the lower block can pull upper block sing the least of the forces.

2. m2g=a(m1+m2)
a=m2g/(m1+m2)