Question

A body of mass 10 kg is displaced from point A(2, 3) to point B(3, 3, 4) under the effect of a force of magnitude 20 N in the direction of $6\hat{i}+8\hat{j}$ calculate W.D by the force

• A. $440J$
• B. $20\sqrt{6}$ J
• C. $44J$
• D. zero

Answer 1

The correct option is A $440J$

$\begin{array}{c}workdone=F\cdot ds\\ =20\left(6\hat{i}+8\hat{j}\right)\cdot \left[\left(3-2\right)\hat{i}+\left(3-1\right)\hat{j}+\left(4-3\right)\hat{k}\right]\\ =20\left(6\hat{i}+8\hat{j}\right)\cdot \left(\hat{i}+\hat{j}+\hat{k}\right)\\ =20\left(6+16\right)\\ =20\times 20\\ =440J\end{array}$

Hence,

option $\left(A\right)$ is correct answer.