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A force of -Fhatk acts on O, the origin ...

A force of `-Fhatk` acts on O, the origin of the coodinate system. The torque about the point (1,-1) is

A

`-F(hati+hatj)`

B

`F(hati+hatj)`

C

`-F(hati-hatj)`

D

`F(hati-hatj)`

Text Solution

Verified by Experts

`vecr=hati-hatj`, `vecF= -Fhatk`
`vectau=vecrxxvecF=(hati-hatj)xx(-Fhatk)`
`= -F[hatixxhatk-hatjxxhatk]`
`= -F[-hatj-hati]=F[hati+hatj]`
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