Question

While two forces act on it, a particle of mass m=3.2kg is it to move continuously with velocity (3m/s)i - (4m/s)j . one of the forces is F1 = (2N)i + (-6N)j . what is the other force?

Answer 1

Mmm tricky.
Since the velocity is constant, I'm going to assume there is no acceleration in any direction. This means there is no net force in the I or J forection!

Since there are 2 forces, both must be equal and opposite in direction to perfectly cancel each other out.

So the opposite of F1 is (-2N)I + (6N)J!