First slide

Work done by Diff type of forces

Question

A string of length L and force constant k is stretched to obtain extension l. It is further stretched to obtain
extension l₁. The work done in second stretching is [MHT CET 2014]

Moderate

A

$\frac{1}{2} k l_{1} (2 l + l_{1})$
B

$\frac{1}{2} k l_{1}^{2}$
C

$\frac{1}{2} k (l^{2} + l_{1}^{2})$
D

$\frac{1}{2} k (l_{1}^{2} - l^{2})$

Solution

Work done in stretching a string to obtain an extension I,
$W_{1} = \frac{1}{2} k l^{2}$
Similarly, work done is stretching a string to obtain extension
$(l + l_{1}), W_{2} = \frac{1}{2} k {(l_{1} + l)}^{2}$
Now, work done in second stretching,
$W_{2} = W_{2}^{'} - W_{1} = \frac{1}{2} k {(l_{1} + l)}^{2} - \frac{1}{2} k l^{2} = \frac{1}{2} k l_{1} (2 l + l_{1})$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App