Question

Which of the following objects is in dynamic equilibrium? A - a man standing in one place without moving B- a bicycle accelerating forward at 1.25 m/s^2 C- a car driving in a circle at a constant speed of 20 m/s D- a motorcycle with a constant velocity

Answer 1

The answer is D- a motorcycle with a constant velocity.

Velocity is much more stable in terms of speed and distance that can be associated with the dynamics of equilibrium (balance) compared to speed alone. It brings the constant relationship between the two elements. 

Speed is only focused on time of travel and not with direction. While acceleration does not show equilibrium but only a change in speed.

Answer 2

Answer:

Option (D)

Explanation:

A dynamic equilibrium is the state in which the net force on the body is zero but the body is moving.

For option (a), A man is standing without moving, it means the man is in static equilibrium.

For option (b), a bicycle accelerating forward with acceleration, it means it is not in dynamic equilibrium.

For option (c), a car driving in circle with a constant speed, it means the direction of speed is changing, so the acceleration is there and the car is not in dynamic equilibrium.

For option (d), a motorcycle with a constant velocity, it means the net force is zero and the motorcycle is in dynamic equilibrium.