Question

The mass of a lift is 2000 kg. When the tension in the supporting cable is 28000 N, then its acceleration is

• A. $30$ ${ms}^{-2}$ downwards
• B. $4$ ${ms}^{-2}$ upwards
• C. $4$ ${ms}^{-2}$ downwards
• D. $14$ ${ms}^{-2}$ upwards

Answer 1

The correct option is B $4$ ${ms}^{-2}$ upwards

Given,

Mass, $m=5000kg$

Tension, $T=28000N$

Acceleration due to gravity, $g=9.8m/s^2$

Therefore,

$T-mg=ma$

$a=\frac{T-mg}{m}$

$=\frac{28000-(2000\times 9.8)}{2000}$

$=\frac{28000-19600}{2000}=\frac{8400}{2000}\approx 4m/s^{2}upwards$