Question

Which statement is true of an object in equilibrium?
a. The sum of all the horizontal lines are non0vertical
b. The sum of all the vertical lines are non0vertical
c. The sum of all forces on the object are zero
d. At least one of the forces on the object is zero

Answer 1

C. The sum of all forces on an object in equilibrium is zero. Equilibrium means in a stationary position. Therefore there is no acceleration. And using Newton's second law, we can say that the net or resultant force is 0. F = ma =>F = m(0) =>F= 0

Answer 2

Answer:

The sum of all forces on the object are zero

Explanation:

An object in equilibrium means it is balanced. In an equilibrium state, the total forces acting on it are balanced so net force is zero and then the system is said to be in equilibrium state.      

For example :  In attached figure, the forces acting in horizontal as well as vertical direction are equal and opposite. This gives the sum of forces acting on the object is zero. So, the system is in balanced state or in equilibrium state.

Hence, the correct option is (c).