Which has zero acceleration? An object
A) at rest.
B) moving at constant velocity.
C) in mechanical equilibrium.
D) all of these
E) none of these
The Correct Answer and Explanation is :
The correct answer is D) all of these.
Explanation:
To understand why the correct answer is “all of these,” let’s break down each option:
A) Object at rest:
An object at rest means that it has zero velocity. According to Newton’s first law of motion, an object at rest will remain at rest unless acted upon by an external force. If no external force is applied to the object, its acceleration is zero. This is a situation where there is no change in velocity, which means zero acceleration.
B) Object moving at constant velocity:
An object moving at a constant velocity means it is traveling at a steady speed in a straight line. In this case, its speed and direction remain unchanged. Acceleration is defined as the rate of change of velocity. Since the velocity is constant (there is no change in speed or direction), the acceleration is zero.
C) Object in mechanical equilibrium:
Mechanical equilibrium refers to a state where the forces acting on an object are balanced. In this case, the net force acting on the object is zero. According to Newton’s second law, ( F = ma ), where ( F ) is the net force, ( m ) is the mass of the object, and ( a ) is the acceleration. If the net force is zero, the acceleration must also be zero. Therefore, an object in mechanical equilibrium has zero acceleration.
D) All of these:
As we can see from the above explanations, in all of these cases—whether the object is at rest, moving with constant velocity, or in mechanical equilibrium—the acceleration is zero. Therefore, the correct answer is “all of these.”
Summary:
Acceleration is the rate at which an object’s velocity changes. If there is no change in velocity (whether an object is at rest, moving at a constant velocity, or in mechanical equilibrium), the object experiences zero acceleration. Thus, all the situations described in the options result in zero acceleration, making “D) all of these” the correct choice.
