Check the dimensional correctness of p = mv
Linear momentum. Momentum is mass times velocity.
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.
p = m vp[M L T-1]=mv[M L T-1]Step by step
2. The dimensions of each term
- p [M L T-1] [M L T-1]
- mv [M] × [L T-1] [M L T-1]
3. Compare
Every term has dimensions [M L T-1], so the equation is dimensionally consistent.
What it proves and what it does not
It can show
- Every term that is added or subtracted has the same dimensions, so the sum makes sense.
- Both sides of the equals sign have the same dimensions.
- Angles inside sin, cos and similar functions are pure numbers.
It cannot show
- A pure number such as 1/2 or 2π has no dimensions, so a check cannot see a missing or wrong one.
- Two quantities with the same dimensions, such as work and torque, cannot be told apart.
- A sign error or a wrong power that keeps the dimensions equal goes unnoticed.
Matching dimensions are necessary but not sufficient. Pure numbers such as 1/2 or 2π have no dimensions, so a check cannot see them, and an equation with matching dimensions can still be wrong.
Look up each quantity
p = mv: quick answers
Is p = mv dimensionally correct?
Yes. Every term has the same dimensions, [M L T⁻¹], so p = mv is dimensionally consistent. That does not prove the equation itself is correct.
Does a dimension check prove p = mv is right?
No. A check can show that an equation is wrong, but it cannot show that it is right. Pure numbers such as 1/2 and 2π have no dimensions, so the check cannot see them.