The moment of the froce, `vecF=4hati+5hatj-6hatk` at `(2,0,-3)`, about the point `(2,-2,-2)` is given by

Options

A. `-7hati-4hatj-8hatk`
B. `-8hati-4hatj-7hatk`
C. `-7hati-8hatj-4hatk`
D. `-4hati-hatj-8hatk`

Answer

A

Explanation

`vecF=4hati+5hatj-6hatk`
`vecr=(2,0,-3)-(2,-2,-2)=(0,2,-1)`
`therefore vectau=vecrxxvecF`
`=(0,2,-1)xx(4,5,-6)`
`=|(hati,hatj,hatk),(0,2,-1),(4,5,-6)|`
`=hati(-12+5)-hatj(4)-hatk(-8)`
`=-7hati-4hatj-8hatk`