Question

A point of application of a force $F=(3i-2j+2k)N$ is displaced by $x=(3i+2j+k)$ metres. Then the work done by the force is (in J)

• A. $5$
  
• B. $7$
  
• C. $9$
  
• D. $11$
  

Answer 1

The correct option is B $7$

Work done by the force is given by $W=F.x$

$\therefore W=(3\hat{i}-2\hat{j}+2\hat{k}).(3\hat{i}+2\hat{j}+\hat{k})$

Or $W=(3\times 3)+(-2\times 2)+(2\times 1)$

Or $W=9-4+2=7J$