# Question #e3483

##### 1 Answer

#### Answer:

Momentum will decrease by **20%**.

#### Explanation:

The idea behind this problem is that *kinetic energy* and *momentum* both use the **velocity** of the object in their expressions.

The equation for an object's kinetic energy looks like this

The equation that describes the momentum of an object is

So, you know that the object's kinetic speed *decreases* by **36%**. This means that it now stands at **64%** of its initial value.

Since the mass of the object is assumed to be constant, this decrease in kinetic energy correlates with a decrease in velocity.

If

Take the square root from both sides of the equation to get

Now use this relationship between the two velocities of the object to express the initial and final momentum

This means that the momentum *decreased* by

Expressed in percentages, this is equivalent to