If the mass of an object doubles, its momentum also doubles, assuming the velocity remains constant.

Here's why:

* Momentum is a measure of an object's mass in motion. It's calculated by the following formula:

Momentum (p) = mass (m) x velocity (v)

* If you double the mass (m) while keeping the velocity (v) the same, the momentum (p) will also double.

Example:

* A car with a mass of 1000 kg traveling at 20 m/s has a momentum of 20,000 kg*m/s.

* If the car's mass doubles to 2000 kg, while still traveling at 20 m/s, its momentum will double to 40,000 kg*m/s.