Question

Three forces act on a moving object. One force has a magnitude of 61.9 N and is directed due north. Another has a magnitude of 52.0 N and is directed due west. What must be (a) the magnitude and (b) the direction of the third force, such that the object continues to move with a constant velocity? Express your answer as a positive angle south of east.

Answer 1

constant velocity means no acceleration, which means zero net force

so the third force is equal in magnitude to the resultant of the given forces; but opposite in direction

the magnitude of the resultant of the given forces is __ sqrt(61.9^2 + 52.0^2)

the tangent of the angle of the resultant (north of west) is __ 61.9/52.0