Chapter 12, Problem 1FTD

Give an example of an object on which the net force is zero, but that isn’t in static equilibrium.

To determine

To provide: An example of an object on which net force is zero, but it isn’t in static equilibrium.

Explanation of Solution

Consider a rotating rod about an axis and two forces acting on the rod is perpendicular to the axis in opposite direction.

Sketch the Free Body Diagram of rod as shown in Figure 1.

Refer Figure 1.

Net force acting on the rod ${\displaystyle \sum F}=0$ and net torque about the center of gravity is ${\displaystyle \sum \tau }\ne 0$.