A car company is testing seatbelts using crash test dummies. The company finds that when cars come to a sudden stop, the crash test dummies' bodies continue to move forward. The seat belt keeps the crash test dummies from hitting the back of the seat in front of them. Why do the crash test dummies' bodies continue to move forward even though the car stopped?

Answer: Because of Inertia

Explanation: According to Newton first law, that a body in a linear motion will continue to be in motion except an external for act on it

But also, a body in motion will always like to continue in motion and have a reluctance tendency to stop because of inertia.

the crash test dummies' bodies will continue to move forward even though the car stopped because of inertia.