An object acted on by three forces moves with constant velocity. One force acting on the object is in the positive direction and has a magnitude of 6.1 ; a second force has a magnitude of 4.0 and points in the negative direction.

Question

Find the direction of the third force acting on the object.

Help plz.
Mag ; ;

Answer 1

Since the object is not accelerating, the net force must be zero.

There must be two forces in the negative direction to cancel out the 6.1 force in the positive direction.

What does that tell you about the third force?

Answer 2

F1+F2+F3 = M*a = M*0 = 0.
6.1 - 4 + F3 = 0.
F3 = -2.1 N. = 2.1 N. Due West.