Question

Jack and Jill are maneuvering a 3100 kg boat near a dock. Initially the boat's position is < 2, 0, 3 > m and its speed is 1.6 m/s. As the boat moves to position < 6, 0, 1 > m, Jack exerts a force of < -440, 0, 220 > N, and Jill exerts a force of < 170, 0, 340 > N.
How much work does Jack do?
How much work does Jill do?

Answer 1

Answer:

(a) work done by Jack is -2200J

(b) work done by Jill is 0

Explanation:

Given;

Initially boat's position =  < 2, 0, 3 > m

Final boat's position = < 6, 0, 1 > m

change in position = < 4, 0, -2 >

Force exerted by Jack =  < -440, 0, 220 > N

Force exerted by Jill = < 170, 0, 340 > N

Part (a) How much work does Jack do?

work done = force x distance

Jack's work = < -440, 0, 220 > N x < 4, 0, -2 > m

                    = [(-440*4) + (0*0) + (220*-2)]

                    = -1760 J - 440 J

                    = -2200J

Part (b) How much work does Jill do?

Jill's work = < 170, 0, 340 > N x < 4, 0, -2> m

                 = [(170*4) + (0*0) + (340*-2)]

                  = 680 J - 680 J

                   = 0