In basic physics, an object that is at rest may still possess which of the following physical quantities?

Introduction / Context:
In elementary mechanics we often distinguish between objects that are moving and those that are at rest. Many learners assume that if an object is at rest it has no mechanical quantities associated with it. This question tests your understanding of which physical quantities depend on motion and which can exist even when the body is not moving at all. Understanding this idea is important for topics such as gravitational potential energy, elastic potential energy, and equilibrium situations in physics.

Given Data / Assumptions:
- The object is explicitly said to be at rest, so its speed is zero.
- The options involve common mechanical quantities: momentum, potential energy, velocity and kinetic energy.
- We assume standard school-level definitions from classical mechanics and no relativistic effects.

Concept / Approach:
In mechanics, some quantities depend directly on velocity, while others depend on position or configuration. Momentum is defined as mass * velocity. Kinetic energy is defined as (1/2) * mass * speed^2. Velocity itself is the rate of change of displacement. All of these quantities become zero when the speed is zero. Potential energy, however, is energy stored due to position or configuration in a force field, such as a raised mass in a gravitational field or a compressed spring. It does not require motion to exist, only a suitable position or configuration relative to a reference level.

Step-by-Step Solution:
Step 1: Note that the object is at rest, so its speed and velocity are zero. Step 2: Momentum p is defined as p = m * v. With v = 0, momentum is zero. Step 3: Kinetic energy K is defined as K = (1/2) * m * v^2. With v = 0, kinetic energy is zero. Step 4: Velocity itself is zero because the object is not changing its position with time. Step 5: Potential energy depends on position in a field, for example m * g * h in a gravitational field, and can be non-zero even when the body is at rest at some height h. Step 6: Therefore, the only listed quantity that an object at rest may still possess is potential energy.

Verification / Alternative check:
Imagine a book resting on a high shelf. It is clearly at rest, but if it falls, it can do work and gain kinetic energy. This ability to do work comes from its gravitational potential energy m * g * h, which exists even though the book is initially at rest. By contrast, a stationary book has no kinetic energy and no momentum because both depend on velocity. This example confirms that potential energy is the correct choice.

Why Other Options Are Wrong:
Momentum: Momentum requires motion (p = m * v). With v = 0, momentum is zero, so a truly resting object has no momentum.
Velocity: If the object is at rest, its displacement does not change with time, so its velocity is zero and not something it "has" as a non-zero quantity.
Kinetic energy: Kinetic energy depends on speed. With speed equal to zero, kinetic energy is also zero and therefore cannot be non-zero for an object at rest.

Common Pitfalls:
A common misconception is to think that if an object is at rest, all forms of mechanical energy must be zero. Students sometimes forget that potential energy is stored energy due to position. Another mistake is to confuse "rest" with having no forces acting. An object can be at rest under balanced forces while still having potential energy. Also, some learners mix up potential and kinetic energy and assume they always come together, which is not true in static situations.

Final Answer:
The only physical quantity that an object at rest may still possess is potential energy.