Question

question 4 of 10
which of the following objects is in dynamic equilibrium?

a. a motorcycle with a constant velocity
b. a car driving in a circle at a constant speed of 20 m/s
c. a man standing in one place without moving
d. a bicycle accelerating forward at 1.25 m/s²

Explanation:

Dynamic equilibrium occurs when an object is moving at a constant velocity (i.e., no net force acting on it).

• Option A: A motorcycle with a constant velocity has no net acceleration ($a = 0$), so net force $F_{net}=ma = 0$ (by Newton's second law $F = ma$). This satisfies dynamic equilibrium.
• Option B: A car driving in a circle at constant speed has a centripetal acceleration (direction of velocity is changing), so there is a net force (centripetal force), not in equilibrium.
• Option C: A man standing still is in static equilibrium (not moving), not dynamic equilibrium.
• Option D: A bicycle accelerating has a non - zero acceleration, so net force is non - zero (by $F = ma$), not in equilibrium.

Answer:

A. A motorcycle with a constant velocity