Question

A lift is moving in upward direction. The total mass of the lift and the passangers is 1600 kg. The variation of the velocity of the lift is as shown in the figure. The tension in the rope at $t=8s$ will be

• A. 11200 N
• B. 16000 N
• C. 48000 N
• D. 12000 N

Answer 1

The correct option is A 11200 N

The speed decreases at $t=8s$, hence the lift is decelerating at this time.

Hence acceleration of lift is downwards and equal to slope of the v-t curve $=\frac{12-0}{10-6}m/s^2=3m/s^2=a$

Therefore, $mg-T=ma$

$⟹T=m(g-a)$

$=1600kg\times (10-3)m/s^2$

$=11200N$