Find the torque of a force ` 7veci+ 3vecj - 5veck` about the origin. The force acts on a particle whose position vector is `veci-veci +veck`.

Explanation

Force `vecF = 7veci + 3vecj - 5veck`
Position of particles `vecr = vec i - vecj + veck`
torque ` t= vecr xx vecF therefore tau = |{:(hati, hatj, hatk),(1, -1, 1), (7, 3, -5):}|`
`therefore tau = veci [ (-1) (-5) -(3xx1)]`
`-hatj [ 1xx (-5) - (7xx1)] + veck [(1xx3) - (-1) xx 7]`
`therefore tau veci (5-3) - vecj (-5-7) + veck(3+7) = 2veci + 12vecj+ 10veck`
magnitude of torque `tau = sqrt(2^2 + 12^2 + 10^2)`
` = sqrt(4+144 +100) = sqrt(248)` units