Question

What can you say about the velocity of a moving body that is in dynamic equilibrium? Draw a sketch of such a body using clearly labeled arrows to represent all external forces on the body.

Short answer

The velocity is constant.

Step-by-step solution

Newton’s first law

According to Newton’s first law, any object continues its state of rest or uniform motion when total external force on that object is zero. The object remains at rest when the object is in static equilibrium.

Explanation

When the object is in dynamic equilibrium, the total force should be zero on that object. For this reason, the acceleration should be zero.

Example

For example, when an object’s weight is downward there is a normal reaction on it acting vertically upward. The object is moving with a constant speed v in the direction of positive X-axis.

If the applied force on the object is F and the frictional force on the object is f. The sum of all the forces is zero, the object will move with a constant velocity v in the direction of positive X-axis.

The diagram is shown below: