#
3 and 4 th ques plzzz with proper sol ..from meritnation experts

Dear Student ,

Moment of inertia of a disc about an axis passing through its centre and perpendicular to its plane is ,

$I=\frac{1}{2}m{r}^{2}$

Now when the radius r' = 2r then ,moment of inertia becomes ,

$I\text{'}=\frac{1}{2}m{\left(2r\right)}^{2}=\frac{1}{2}m\times 4{r}^{2}=4\times \frac{1}{2}m{r}^{2}=4I$

Here is a link for the question number 4 which will help you to solve this question with proper explanation .

https://www.meritnation.com/ask-answer/question/explain-four-point-masses-each-of-value-m-are-placed-at-the/system-of-particles-and-rotational-motion/10718963

Regards

**
**