First slide

Two block problem

Question

A 4 kg block A is placed on the top of 8 kg block B which rests on a smooth table.
A just slips on B when a force of 12 N is applied on A. Then, the maximum horizontal force F applied on
B to make both A and B move together, is

Difficult

A

12 N
B

24 N
C

36 N
D

48 N

Solution

When force is applied on A, acceleration produced will be
$\frac{F_{A}}{m_{A} + m_{B}} = \frac{μ m_{A} g}{m_{B}}$ …(i)
When force is applied on B, acceleration produced will be
$\frac{F_{B}}{m_{A} + m_{B}} = \frac{μ m_{A} g}{m_{A}}$ …(ii)
Dividing these two equations, we get
$\frac{F_{B}}{F_{A}} = \frac{m_{B}}{m_{A}}$
$∴ F_{B} = \frac{m_{B}}{m_{A}} \cdot F_{A} = \frac{8}{4} \times 12 = 24 N$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App