Question 7: A point object acted on by forces of 4N, 5N and 6N is in equilibrium. If 6N force is removed, what is the resultant force on the object?
When a body is in equilibrium, the sum of the forces acting on it is zero. If the body is under the influence of more than two forces of different magnitudes, they will be acting at such angles that the resultant force of all of them is zero (And remember force is a directed quantity).
In the given problem, the body is in equilibrium under the action of three forces of magnitudes 4N, 5N and 6N. This means that all forces are cancelling the effect of one another. Clearly, the sum of 4N and 5N force is 6N, which has balanced the third force of 6N. If the 6N force is removed, the body is left with a resultant of 6N force. The remaining forces of 4N and 5N are adjusted so that their resultant was 6N, which had balanced the force that is removed.