1. what is the momentum of a running back with a mass of 100 kg at a velocity of 4 meters per second?

Explanation:

Step1: Recall momentum formula

The formula for momentum $p$ is $p = m\times v$, where $m$ is mass and $v$ is velocity.

Step2: Substitute values

Given $m = 100\ kg$ and $v=4\ m/s$, we substitute into the formula: $p=100\times4$.

Step3: Calculate result

$p = 400\ kg\cdot m/s$.

Answer:

$400\ kg\cdot m/s$