Question

Find the value of friction forces between the blocks A and B and between B and ground. (Take $g=10m/s^2$)

• A. $90N,5N$
• B. $5N,90N$
• C. $5N,75N$
• D. $0N,80N$

Answer 1

The correct option is D $0N,80N$

In the given figure,

taking $(A+B)$ as system

$f_{s}max$ between surface of $B$ and earth is $120N$

$\therefore$ The block will not move

$\therefore$ There is no acceleration of any block

$\therefore$ Net force on block is zero

frictional force on $A=0N$

and frictional force on $B=80N$