Q.
A block $A$ weighing 100 kg rests on a block $B$ and is tied with a horizontal string to the wall at$\ C$. Block $B$ weighs 200kg. The coefficient of friction between $A$ and $B$ is$\ 0.25\ $and between $B$ and the surface is$\ \frac{1}{3}$. The horizontal force $P$ necessary to move the block $B$ should be $\left( g = 10\frac{m}{s^{2}} \right)$
A) 1150 N
B) 1250 N
C) 1300 N
D) 1420 N
Explanation
(b) Friction between block A and block B and between block B and surface will oppose the P.
$\therefore P = F_{AB} + F_{BS}$
$\mu_{AB}m_{a}g + \mu_{BS}\left( m_{A} + m_{B} \right)g$
$= 0.25 \times 100 \times 10 + \frac{1}{2}(100 + 200) \times 10 = 1250\ N$
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Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.