Question

If there is a change of angular momentum from 1 j-s to 4j-s in 4 s, then the torque

Options

• `(5/4)"J"`

• `(3/4)"J"`

• 1 J

• `(4/3)"J"`

Answer 1

`(3/4)"J"`

Explanation:

In rotational motion, the relation between torque and angular momentum L is

𝜏 = `"dL"/"dt"`

Here, dL = (4 - 1) = 3 J-s

and dt = 4s

∴ 𝜏 `=(3"J-s")/(4"s")=3/4"J"`

OR

L₁ = 1 Js      L₂ = 4 Js

t = 4

`tau=(4-1)/4=3/4J`