Force (5, 6, 7) N acts on a particle with position vector (2, 2, 1) m. The magnitude of `phi` torque on the particle will be ………. Nm.

Options

A. `sqrt(13)`
B. `sqrt(149)`
C. `sqrt(61)`
D. `sqrt(23)`

Answer

B

Explanation

`|vectau|=|vecrxxvecF|`
`=|(2,2,1)xx(5,6,7)|`
`=|(2,2,1)xx(5,6,7)|`
`=|hati(14-6)-hatj(14-5)+hatk(12-10)|`
`=|8hati-9hatj+2hatk|`
`=sqrt((8)^(2)+(-9)^(2)+(2)^(2))`
`=sqrt(64+81+4)`
`=sqrt(149)`