A point of application of a force $\overrightarrow{F}=5\hat{i}-3\hat{j}+2\hat{k}$  is moved from ${\overrightarrow{r}}_1=2\hat{i}+7\hat{j}+4\hat{k}$  top ${\overrightarrow{r}}_2=-5\hat{i}+2\hat{j}+3\hat{k}$  The work done is:

Displacement of the point is

${\overrightarrow{r}}_2-{\overrightarrow{r}}_1=\left(-5\hat{i}+2\hat{j}+3\hat{k}\right)-\left(2\hat{i}+7\hat{j}+4\hat{k}\right)$

$=-7\hat{i}-5\hat{j}-\hat{k}$

Work done $W=\overrightarrow{F}.\left({\overrightarrow{r}}_2-{\overrightarrow{r}}_1\right)$

$=\left(5\hat{i}-3\hat{j}+2\hat{k}\right).\left(-7\hat{i}-5\hat{j}-\hat{k}\right)$

$=-35+15-2$

$=-22\text{unit}$