Examples

Example: Calculating the momentum of a slow-moving object

A 1971 Ford Pinto is observed to moving with a velocity of $\langle 22.35,0,1.06\rangle\frac{m}{s}$. Determine the momentum of this sweet ride.

Setup

You need to compute the momentum of a 1971 Ford Pinto using the information provided and any information that you can collect or assume.

Facts

• The Ford Pinto is in motion
• It has a velocity, ${\overset{\rightarrow}{v}}_{car} = \langle 22.35,0,1.06\rangle\frac{m}{s}$.

Lacking

• The mass of the Ford Pinto is not given, but can be found online ($m_{car} = 884.05kg$).

Approximations & Assumptions

• The Ford Pinto experiences several forces, but over the short time we are looking at it, it experiences no net force, so its velocity will remain unchanged.
• The velocity of the Ford Pinto is much less than the speed of light ($|{\overset{\rightarrow}{v}}_{car}| \ll c = 3.00 \times 10^{8}\frac{m}{s}$).

Representations

• The momentum of the Ford Pinto is given by $\overset{\rightarrow}{p} = m\overset{\rightarrow}{v}$.

Solution

We compute the momentum vector.