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If the resultant of three forces vecF1 =...

If the resultant of three forces `vecF_1 = p hati + 3hatj -hatk, vecF_2 = 6hati-hatk and vecF_3 =-5hati +hatj +2hatk` acting on a particle has a magnitude equal to 5 units, then the value of `p` is

A

`-6`

B

`-4`

C

2

D

4

Text Solution

Verified by Experts

The correct Answer is:
B, C
Let `vecR` be the resultant. Then
`vecR= vecF_1 + vecF_2 + vecF_3 = (p+1) veci + 4hatj`
Given, `|vecR| =5`. Therefore,
`(p+1)^(2)+ 16 = 25
or `p+1 = pm3`
or `p=2, -4`
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