A boy of mass 1 kg moves from point $A(2m,3m,4m)$ to $B(3m,2m,5m)$. During motion of body, a force $\overrightarrow{\mathbf{F}} = (2N)\widehat{\mathbf{i}} - (4N)\widehat{\mathbf{j}}$ acts on it. The work done by the force on the particle displacement is

Question

Dr. Abubacker · Accepted Answer

(c) The displacement of body is
$\overrightarrow{\mathbf{AB}} = {\overrightarrow{\mathbf{r}_{\mathbf{\ }}}}_{B} - {\overrightarrow{\mathbf{r}}}_{A}$
$= \left( 3\widehat{\mathbf{i}} + 2\widehat{\mathbf{j}} + 5\widehat{\mathbf{k}} ight) - (2\widehat{\mathbf{i}} + 3\widehat{\mathbf{j}} + 4\widehat{\mathbf{k}})$
$= \widehat{\mathbf{i}} + \widehat{\mathbf{j}} + \widehat{\mathbf{k}}$
$	herefore\ W = \overrightarrow{\mathbf{F}}.\overrightarrow{\mathbf{AB}} = (2\widehat{\mathbf{i}} - 4\widehat{\mathbf{j}}).(\ \widehat{\mathbf{i}} - \widehat{\mathbf{j}} + \widehat{\mathbf{k}})$
$= 2 - 4 = - 2\ J$

Q. A boy of mass 1 kg moves from point $A(2m,3m,4m)$ to $B(3m,2m,5m)$. During motion of body, a force $\overrightarrow{\mathbf{F}} = (2N)\widehat{\mathbf{i}} - (4N)\widehat{\mathbf{j}}$ acts on it. The work done by the force on the particle displacement is

Explanation

Reviewed by Dr. Abubacker

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