Two mutually perpendicular common point forces F1 and F2 act on the same object and make the object move for a period of displacement. If F1 does 4J work on the object, F2 does 5J work on the object How much work do they work together? Write down the reasons

Two mutually perpendicular common point forces F1 and F2 act on the same object and make the object move for a period of displacement. If F1 does 4J work on the object, F2 does 5J work on the object How much work do they work together? Write down the reasons

The work done by the resultant force is equal to the algebraic sum of the work done by each component force (the work done by each component force is positive or negative), and has nothing to do with the angle between the components, so the work done by the resultant force is 5 + 4 = 9j

Given the displacement S = (2lg5,1) of a body under the action of the common point forces F1 = (LG2, LG2) and F2 = (lg5, LG2), then the total work W of the two common point forces on the body is ()
A. 1B. 2C. lg2D. lg5

∵ F1 + F2 = (LG2, LG2) + (lg5, LG2) = (1, 2lg2) and ∵ displacement S = (2lg5, 1) ∵ the total work of the two forces on the object W is (1, 2lg2) · (2lg5, 1) = 2lg5 + 2lg2 = 2, so B is selected

When one of the forces F1 stops acting on the same object, the following judgment is correct
Object a moves in the direction of F1, object B moves in the opposite direction of F1, and Object C remains stationary. Because the number of common point forces is unknown, it is impossible to judge the motion of the object

D right, for example, you use two ropes with a certain angle to hang a small ball on the roof, and then cut one of the ropes. How do you think the ball should move?