Numford

GravitationClass 11, Gravitation

Dimensional formula of Acceleration due to gravity

[L T-2]

Symbolg SI unitmetre per second squared (m/s²)

The acceleration of a falling body, GM/R² at the surface. It has the dimension of any acceleration.

Derivation

How to get the dimensional formula of acceleration due to gravity

  1. Start from the definition: acceleration due to gravity = gravitational constant × mass / length2.
  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] / [L]2.
  7. Add the powers of each base quantity: [L T-2].
Same dimensions

Quantities with the dimensions [L T⁻²]

Equal dimensions do not make them the same quantity. Compare acceleration due to gravity with the others in the full grid.

Practice

Three questions on acceleration due to gravity

1Which of these has the same dimensions as acceleration due to gravity?

2What is the SI unit of acceleration due to gravity?

3Which one has different dimensions from the others?

Try it

An equation that uses acceleration due to gravity

Equation checker

Matching dimensions are necessary, not sufficient. A check cannot see pure numbers such as 1/2 or 2π, so a consistent equation can still be wrong.

Read asT = 2 π sqrt(l / g)
T[T]2 pi sqrt(l/g)[T]
Dimensionally consistentEvery term is [T]
l = lengthg = acceleration due to gravity
Questions

Acceleration due to gravity: quick answers

What is the dimensional formula of acceleration due to gravity?

The dimensional formula of acceleration due to gravity is [L T⁻²]. It comes from acceleration due to gravity = gravitational constant × mass / length².

What is the SI unit of acceleration due to gravity?

The SI unit of acceleration due to gravity is the metre per second squared (m/s²).

Which quantities have the same dimensions as acceleration due to gravity?

Acceleration due to gravity shares [L T⁻²] with acceleration, gravitational field intensity. Equal dimensions do not make them the same quantity.

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