Physics · Work, Energy And Power · NEET
Yes. NCERT itself says potential energy is the 'stored energy' by virtue of the position or configuration of a body. A stretched bow-string or a compressed spring stores this energy. When the body is left free, it releases the stored energy as kinetic energy (motion).
No. This is the key idea. A ball resting on a shelf is not moving, yet it has potential energy because of its height. Motion gives kinetic energy; position or shape gives potential energy. A body can have potential energy while completely at rest.
Kinetic energy is the energy of motion (KE = 1/2 m v squared). Potential energy is stored energy of position or shape. When a raised body falls, its potential energy converts into kinetic energy. So they are two forms of mechanical energy that can change into each other.
Yes. Potential energy is always measured relative to a chosen reference level (where you set PE = 0). If a body is below that reference, its PE comes out negative. Only the change in PE and the reference point are physically meaningful, not the absolute number.
Because potential energy is stored by the arrangement of the system against a force. Gravitational PE depends on height h because gravity acts over that height; spring PE depends on the stretch x because the spring resists it. Speed decides kinetic energy, not potential energy.
Potential energy is a scalar. Like all forms of energy, it has magnitude and a unit (joule) but no direction. You add potential energies as plain numbers, not as vectors.
A particle is released from height S from the surface of the Earth. At a certain height its kinetic energy is three times its potential energy. The height from the surface of the Earth and the speed of the particle at that instant are respectively:
The potential energy of a spring when stretched by 2 cm is U. If the spring is stretched by 8 cm, the potential energy stored in it will be:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Potential energy is energy a body has just because of where it is (its position) or how it is stretched or compressed (its shape). It is stored energy that can turn into motion energy when the body is released.
The two types you use most are gravitational potential energy (due to height, PE = mgh) and elastic or spring potential energy (due to stretch or compression, PE = 1/2 k x squared). Both are stored energy of position or shape.
The SI unit of potential energy is the joule (J), the same as every other form of energy. Its dimensional formula is [M L squared T to the power minus 2].
Potential energy is the base for conservation of mechanical energy, spring problems, projectile and free-fall questions, and collisions. NEET regularly converts PE into KE (and back) to test energy conservation, as in the 2021 and 2023 questions above.
For conservative forces like gravity and spring force, potential energy depends only on the start and end positions, not on the path. That is exactly what lets us define a stored PE for these forces.
