Numford

GravitationClass 11, Gravitation

Dimensional formula of Gravitational potential energy

[M L2 T-2]

SymbolU SI unitjoule (J)

The energy of two masses at a distance, -GMm/r. It has the dimension of energy.

Derivation

How to get the dimensional formula of gravitational potential energy

  1. Start from the definition: gravitational potential energy = gravitational constant × mass2 / length.
  2. velocity = length / time, so velocity is [L] / [T] = [L T-1].
  3. acceleration = velocity / time, so acceleration is [L T-1] / [T] = [L T-2].
  4. force = mass × acceleration, so force is [M] × [L T-2] = [M L T-2].
  5. gravitational constant = force × length2 / mass2, so gravitational constant is [M L T-2] × [L]2 / [M]2 = [M-1 L3 T-2].
  6. Put in the dimension of each part: [M-1 L3 T-2] × [M]2 / [L].
  7. Add the powers of each base quantity: [M L2 T-2].
Same dimensions

Quantities with the dimensions [M L² T⁻²]

Equal dimensions do not make them the same quantity. Compare gravitational potential energy with the others in the full grid.

Practice

Three questions on gravitational potential energy

1Which of these has the same dimensions as gravitational potential energy?

2What is the SI unit of gravitational potential energy?

3Which one has different dimensions from the others?

Questions

Gravitational potential energy: quick answers

What is the dimensional formula of gravitational potential energy?

The dimensional formula of gravitational potential energy is [M L² T⁻²]. It comes from gravitational potential energy = gravitational constant × mass² / length.

What is the SI unit of gravitational potential energy?

The SI unit of gravitational potential energy is the joule (J).

Which quantities have the same dimensions as gravitational potential energy?

Gravitational potential energy shares [M L² T⁻²] with work, energy, kinetic energy, potential energy, torque, torsional constant, strain energy, heat. Equal dimensions do not make them the same quantity.

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