Ncert Exercises & Solutions

When a disc rotates with uniform angular velocity, which of the following is not true?

1.	the sense of rotation remains the same.
2.	the orientation of the axis of rotation remains the same.
3.	the speed of rotation is non-zero and remains the same.
4.	the angular acceleration is non-zero and remains the same.

(d) Hint: For uniform angular velocity, the angular acceleration is zero.

Step 1: Find rhe angular acceleration.

We know that angular acceleration

$α = \frac{dω}{dt} given ω = constant$

where is the angular velocity of the disc
$\Rightarrow α = \frac{dω}{dt} = \frac{0}{dt} = 0$
Hence, angular acceleration is zero.