Question

A particle of $4kg$ has an initial velocity of $3\hat{i}+4\hat{j}$. It is pushed by force $a\hat{i}+b\hat{j}$, and after sometime velocity becomes $7\hat{i}+24\hat{j}$. Then the work done by force during the interval is

• A. $1000J$
• B. $(7a+24b)J$
• C. $1200J$
• D. $1200J$

Answer 1

The correct option is D $1200J$

$W=\Delta KE$
$=K{E}_f-K{E}_i$
$=\frac{1}{2}.4.(7^2+{24}^2)-\frac{1}{2}.4.(3^2+4^2)$
$=2\left(625\right)-2\left(25\right)$
$=2\left(600\right)=1200\text{J}$