Find the work done by the force F = 9i − 7j in moving an object from the point (3, 7) to the point (4, −15).

Question

Find the work done by the force F = 9i − 7j in moving an object from the point (3, 7)

 to the point (4, −15).

Answer 1

First calculate the vector x from the starting point to the end point.

That is done by subtracting the two points

x = i - 22j

Work W is defined as the dot-product between the force F acting on the object

and the vector of displacement x.

W = F.x = (9i - 7j).(i - 22j) = 9×1 + (-7)×(-22) = 163