Question

A particle moves from position $3\hat{i}+2\hat{j}+6\hat{k}$ to $14\hat{i}+13\hat{j}+9\hat{k}$ due to a uniform force of $4\hat{i}+\hat{j}+3\hat{k}\,N$ . Find the work done, if the displacement is in metre.

• A. 16 J
• B. 64 J
• C. 32 J
• D. 48 J

Answer 1

Answer: (B)

64 J

Answer 2

The correct answer is B:64 J
Work done $= F \cdot d$
$= (4 \hat i + \hat j + 3 \hat k) \cdot[(14 - 3) \hat i + (13 - 2) \hat k + (9 - 6) \hat k]$
$= (4 \hat i + \hat j + 3 \hat k)\cdot (11 \hat i + 11 \hat j + 3 \hat k)$
$= 44 + 11 + 9 = 64 \, J$