Question

A block of mass $300kg$ is set into motion on a frictionless horizontal surface with the help of frictionless pulley and a rope system as shown in the figure. What horizontal force $F$ should be applied to produce in the block an acceleration of $1m/s^2$?

• A. $150N$
• B. $100N$
• C. $300N$
• D. $50N$

Answer 1

The correct option is A $150N$

As shown in the figure, when force $F$ is applied at the end of the string, the tension in lower part of the string is also $F$. If $T$ is the tension in string connecting the pulley and the block, then,
$T=2F$
But $T=\left(200\right)\left(1\right)=200N$
$\therefore 2F=200N$
or $F=100N$