Question

어
a
7. A block of mass m is placed on another block of mass M
which itself is lying on a horizontal surface. The coefficient
of friction between two blocks is u, and that between
the block of block M and horizontal surface is
Mz.
What
maximum horizontal force can be applied to the lower
block so that the two blocks move without separation?
m
M
F
(a) (M+ m) (U2 - Uyg
(b) (M – m) (U2 - 4,8
(d) (M + m) (u2 + )8
(c) (M-m) (U2 + Uz)g​

Answer 1

Explanation:

Here, the force applied should be such that frictional force Acting on the upper block of m should not be more than the Limiting friction (=μ1mg).

For non-slipping condition

Force in upper block f≤μmg (limiting friction)

ma=μ1mg

a= μ1g........(1)

Friction force on mass M, is μ2(M+m)g

Let the system moves with Acceleration a . Then for whole system:

F−μ2 (M+m)g=(M+m)a.........(2)

From equations (1) and (2), we get

F=(M+m)g(μ1+μ2).