Question

An elevator of mass M is pulled upwards by a cable; the elevator has a positive, but decreasing, velocity. What is the tension in the cable (neglecting the mass of the cable)

Answer 1

Answer:

Less than $Mg$

Explanation:

As the elevator is being pulled up the velocity is decreasing that means it has negative acceleration.

The force equation will be as follows

$F-Mg=Ma\\\Rightarrow F=Ma+Mg$

where

$M=\text{Mass of elevator}$

$g=\text{Acceleration due to gravity}$

$a=\text{Acceleration of the elevator}$

$F=\text{Force or tension in the cable}$

Here the value of $a$ is negative as the elevator is slowing down so the tension on the cable will be less than the actual weight $(Mg)$ of the elevator.