In the context of conservation of energy, what does it mean if the net force $=$ $0$ on an object?

• A. The object must be at rest and its energy is $0$.
• B. The object is accelerating and its kinetic energy is increasing.
• C. The object moves with constant velocity and its kinetic energy remains unchanged.
• D. The object is losing energy due to friction.

Answer: (C)

Verified step by step guidance

1. Recall that the net force on an object is related to its acceleration by Newton's second law: \(\vec{F}_{\text{net}} = m \vec{a}\), where \(m\) is the mass and \(\vec{a}\) is the acceleration.
2. If the net force \(\vec{F}_{\text{net}} = 0\), then from Newton's second law, the acceleration \(\vec{a} = 0\).
3. Zero acceleration means the object's velocity is constant; it could be at rest or moving at a constant speed in a straight line.
4. Since the velocity is constant, the kinetic energy, which depends on velocity as \(K = \frac{1}{2} m v^2\), remains unchanged over time.
5. Therefore, in the context of conservation of energy, a zero net force implies no change in kinetic energy and motion with constant velocity.