Question

A $20\text{kg}$ monkey slides down a vertical rope with a constant acceleration of $7{\text{m/s}}^2$. If $g=10{\text{m/s}}^2$, what is the tension in the rope ?

• A. $140\text{N}$
• B. $100\text{N}$
• C. $60\text{N}$
• D. $30\text{N}$

Answer 1

The correct option is C $60\text{N}$

Monkey is sliding down a vertical rope, so the rope will apply a force (i.e tension $T$) on monkey in vertically upward direction.
This can be understood from newton's $3^{rd}$ law i.e while moving downward, monkey will pull rope in downward direction. Hence rope will cause a pull on the monkey in UPWARD direction.

From the FBD of monkey:-

Applying Newton's $2^{nd}$ law in the direction of acceleration:-

$mg-T=ma$

$\Rightarrow 200-T=20\times 7$

$\therefore T=200-140=60\text{N}$