बिंदु `(2 ,0,-3)` पर कार्यरत बल `vecF=4hati+5htj-6hatk` का बिंदु `(2,-2,-2)` के परितः आघूर्ण होगा -

Options

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

Answer

D

Explanation

`vec(r_(a))=2hati+0hatj-3hatk, vec(r_(1))=2hati-2hatj-2hatk`
`vec(tau)=vecr xxvecF=(vec(r_(1))-vec(r_(2)))xxvecF`
`=(2hati+0hatj-3hatk-2hatj+2hatj+2hatk)xx(4hati+5hatj-6hatk)`
`=(0hati+2hatj-hatk)xx(4hati+5hatj-6hatk)=-7hati-4hatj-8hatk.`