The figure shows two forces acting on an object.They have magnitudes F₁ = 6.3 N and F₂ = 2.1 N.What third force will cause the object to be in equilibrium?

Question

Quizplus · Accepted Answer

For the object to be in equilibrium, the net force acting on it must be zero. This means the third force must be equal in magnitude but opposite in direction to the vector sum of the other two forces.

To determine the direction and magnitude of the vector sum of the other two forces, we can use the parallelogram method or the head-to-tail method. Drawing to scale, we can see that the vector sum of the two given forces has a magnitude of 6.6 N and makes an angle of 162° counterclockwise from the horizontal (see image).

Therefore, the third force must have a magnitude of 6.6 N and make an angle of 162° clockwise from the horizontal, which is equivalent to 162° counterclockwise from the vector sum of the other two forces. This matches choice A.

The Figure Shows Two Forces Acting on an Object