Question

The torque of force `F = -3 hat(i)+hat(j) + 5 hat(k)` acting on a point `r = 7 hat(i) + 3 hat(j) + hat(k)` about origin will be
A. `14 hat(i)-38 hat(j) + 16 hat(k)`
B. `4 hat(i)+4hat(j)+6 hat(k)`
C. `-14 hat(i)+38 hat(j)-16 hat(k)`
D. `-21 hat(i)+3 hat(j)+5 hat(k)`

Answer 1

Correct Answer - A
Torque of the force, `tau = r xx F`
`tau=|{:(hat(i),hat(j),hat(k)),(7,3,1),(-3,1,5):}|=(14 hat(i)-38hat(j)+16hat(k))`.