Question

Calculate the work done by a force F specified by: F=3í+4j+5k In displacing body from position B to position A along a straight path . the possition vector A and B are respectively given as: rA= 2i+5j-2k rB=7i+3j-5k

Answer 1

Explanation:

rA=2i+5j-2k

rB=7i+3j-5k

r=rA-rB=2i+5j-2k–(7i+3j-5k)

r=2i+5j-2k–7i–3j+5k=–5i+2j+3k

and F=3í+4j+5k (given)

W=F.r

=(3í+4j+5k).(-5i+2j+3k)

=–15+8+15

=8J