Question

a force of magnitude 10n is applied in the directions 3i-4j to displacement point of action from A to B of position vectors 2i+j,5i-2j respectively. Find the work done. ​

Answer 1

An object at point A moving to point B is displaced in the direction of

r = (5i - 2j) m - (2i + j) m = (3i - 3j) m

(I assume distance is measured in meters)

If the force is F = (10 N) (3i - 4j), then the work performed by F in the direction of r is

F • r = (10 N) (3i - 4j) • (3i - 3j) m = (10 N) (9 + 12) m = 210 J