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Find the torque of a force (7 hati + 3ha...

Find the torque of a force `(7 hati + 3hatj - 5hatk)` about the origin. The force acts on a particle whose position vector is `(hati - hatj + hatk)`.

A

`2hati-12hatj+10hatk`

B

`2hati+12hatj+10hatk`

C

`2hati-12hatj-10hatk`

D

`2hati+12hatj-10hatk`

Text Solution

Verified by Experts

The correct Answer is:
B
Given, positive vector, `r=hati-hatj+hatk`
Force, `F=7hati+3hatj-5hatk`
Torque, `tau=r xx F=|(hati,hatj,hatk),(1,-1,1),(7,3,-5)|`
`=(5-3)hati-(-5-7)hatj+(3+7)hatk`
`=2hati+12hatj+10hatk`
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