Question

The force represented 5i+k is acting through the point 9i-j+2k. Find the moment about the point 3i-2j+2k

Answer 1

Answer:

Here, F=5j+k,O=3i−2j+k,P=9j−j+2k.

∴r=

OP

=P.V of P−P.Vof O

=(9i−j+2k)−(3i−2j+k)=6i+j+k.

∴ Moment, M=r×F=(6i+j+k)×(5j+k)

=

∣

∣

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i

6

0

j

1

5

k

1

1

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=−4i−6j+30k.