Question

A person of mass 60 kg is inside a lift of mass 940 kg and presses the button one control panel. The lift starts moving upwards with an acceleration of 1.0 m/s². If g = 10 ms^–2, the tension in the supporting cable is

1. 1200 N
2. 8600 N
3. 9680 N
4. 11000 N

Answer 1

Correct Answer - Option 4 : 11000 N

CONCEPT:

• Tension: Tension is the magnitude of the force exerted by a chain or a rope or a string. 
• Net Force is (always) equal to the mass times the acceleration.

.F_net = T - mg = ma

T = mg +ma

T = m (g + a)

EXPLANATION:

• Here, Mass of a person, m = 60 kg
• Mass of lift, M = 940 kg,
• a = 1m/s^2 , g = 10 m/s^2

Let T be the tension in the supporting cable

∴ T - (M + m) g = (M + m) a

T = (M+m) (a+g)

= (940 + 60) (1 +10) = 11000 N

option 4 is answer.