# Relativistic Momentum help

1. May 20, 2015

### Cell_52797

1. The problem statement, all variables and given/known data
If a mass of 1 kg has a velocity of 0.7c, what is the relativistic momentum?

2. Relevant equations
I dont know what equation to use....

2. May 20, 2015

### Bandersnatch

Start by writing down the equation for the regular, non-relativistic momentum.

Do you know any relativistic equations for any of the values making up the momentum equation?

3. May 21, 2015

### theodoros.mihos

Relativistic momentum on 4D Minkowski space have 4 coordinates.
$$p_i=mv_i,\,p_{ct} = mc$$
Consevation for this momentoum:
$$\Delta{x}^2+\Delta{y}^2+\Delta{z}^2-c^2\Delta{t}^2=\text{const}$$
give:
$$m=\frac{m_0}{\sqrt{1-(v/c)^2}}$$
where m0 is the mass for its own frame.

4. May 25, 2015

### Cell_52797

No, haha... I am terrible at physics...