Chapter 2, Problem 7RAT

The equilibrium rule, $\sum \text{F=0}$ , applies to

(a) objects or systems at rest.

(b) objects or systems in uniform motion in a straight line.

(c) both of these.

(d) none of these.

To determine

The correct option for the statement " The equilibrium rule,$\sum \text{F=0}$ , applies to".

Answer to Problem 7RAT

The correct option for the statement " The equilibrium rule,$\sum F=0$ , applies to" is option (c).

Explanation of Solution

The equilibrium rule or condition states that the summation of all the forces operating over a body in a particular x, y, and z-direction becomes zero. Along with forces, the net resultant torsion effect operating on the body in a particular direction also becomes zero in magnitude.

This condition is only applicable when the body remains stationary or moving in a straight path with constant speed. Otherwise, if the body is in rotational motion or oscillation, the direction of forces acting over a body changes continuously, and it can't be balanced. From this, it is concluded that option (c) will be correct in the given options.

Conclusion:

Therefore, the correct option for the statement " The equilibrium rule,$\sum F=0$ , applies to" is option (c).