1Which of these has the same dimensions as impulse?
Impulse and photon momentum both have the dimensions [M L T⁻¹].
MechanicsClass 11, Laws of Motion
Dimensional formula of Impulse
[M L T-1]
Force times the time it acts. It has the same dimension as momentum.
How to get the dimensional formula of impulse
- Start from the definition: impulse = force × time.
- velocity = length / time, so velocity is [L] / [T] = [L T-1].
- acceleration = velocity / time, so acceleration is [L T-1] / [T] = [L T-2].
- force = mass × acceleration, so force is [M] × [L T-2] = [M L T-2].
- Put in the dimension of each part: [M L T-2] × [T].
- Add the powers of each base quantity: [M L T-1].
Quantities with the dimensions [M L T⁻¹]
Equal dimensions do not make them the same quantity. Compare impulse with the others in the full grid.
Three questions on impulse
2What is the SI unit of impulse?
The SI unit of impulse is the newton second (N s).
3Which one has different dimensions from the others?
Torsional constant is [M L² T⁻²]. The other three are all [M L T⁻¹].
Impulse: quick answers
What is the dimensional formula of impulse?
The dimensional formula of impulse is [M L T⁻¹]. It comes from impulse = force × time.
What is the SI unit of impulse?
The SI unit of impulse is the newton second (N s).
Which quantities have the same dimensions as impulse?
Impulse shares [M L T⁻¹] with momentum, photon momentum. Equal dimensions do not make them the same quantity.