Question

A 21.0 kg child is running at a velocity of 2.50 m/s. The child is carrying a 2.25 kg gallon of milk. What is the momentum of the child and the milk together?

Answer 1

Answer: The momentum of the child and milk together is 58.125 kg.m/s

Explanation:

Momentum is defined as the product of object's mass and velocity.

Mathematically,

$p=mv$

where, p = momentum

m = mass of the object

v = velocity of the object

In the given question, we are given that a child of mass 21.0 kg is carrying a gallon of milk having mass 2.25 kg and running with a velocity of 2.5 m/s. Hence, the momentum by both milk and child will be:

$p=(m_{child}+m_{milk})v$     ....(1)

Given:

$m_{child}=21.0kg\\m_{milk}=2.25kg\\v=2.5m/s\\p=?kg.m/s$

Putting values in equation 1, we get:

$p=(21+2.25)kg\times 2.5m/s=58.125kg.m/s$

Hence, the momentum of the child and milk together is 58.125 kg.m/s