Applied Mechanics - Engineering

Q1:

The tension in a cable supporting a lift

A is more when the lift is moving downwards

B is less when the lift is moving upwards

C remains constant whether its moves downwards or upwards

D is less when the lift is moving downwards.

ANS:D - is less when the lift is moving downwards.

Acceleration is produced due to the net force.
So, when lift moving downward net force will be T-mg and it generates -ve acceleration that is downward direction.
T-mg =-ma.
T = mg-ma which is less. As upward tension in cable is= T+mg.
As downward tension in cable = T-mg.
So, it shows that the downward is being substracted so it is less.