An object moves along a straight line path from $P$ to $Q$ under the action of a force ($4\widehat{i} - 3\widehat{j} + 3\widehat{k}$)N. If the coordinates of $P$ and $Q$, in metres, are (3,3,$- 1$) and (2,$- 1,4$) respectively, then the work done by the force is

Question

Dr. Abubacker · Accepted Answer

(a) $\left( \overrightarrow{PO} \right) = \overrightarrow{r} = (2 - 3)\widehat{i} + ( - 1 - 3)\widehat{j} + (4 + 1)\widehat{k}$
$= - 1\widehat{i} - 4\widehat{j} + 5\widehat{k}$
Work done $= \overrightarrow{F} \bullet \overrightarrow{r}$
$= \left( 4\widehat{i} - 3\widehat{j} + 3\widehat{k} \right) \bullet ( - 1\widehat{i} - 4\widehat{j} + 5\widehat{k})$
$= - 4 + 12 + 15 = 23\ $J

Q. An object moves along a straight line path from $P$ to $Q$ under the action of a force ($4\widehat{i} - 3\widehat{j} + 3\widehat{k}$)N. If the coordinates of $P$ and $Q$, in metres, are (3,3,$- 1$) and (2,$- 1,4$) respectively, then the work done by the force is

Explanation

Reviewed by Dr. Abubacker

Want more practice?