In terms of motion, what are you feeling when you lurch forward upon slamming on the breaks?

Question

Is this because of inertia or something else?

Answer 1

Inertia is right. Newton's first law.

Both you and the car are moving. The car stops. Your body continues to move due to inertia as per newton's first law. Hence you move forward within the car, and if you're restrained by a seat belt, lurch forward.

Here's an interesting experiment. Will anything "lurch" backwards when you brake? Buy a helium baloon and let it float in the car and see how it moves when you brake. Also observe how a passenger and the baloon move when the car turns sharply to the left or right. Keep in mind Helium has a lower density than the surrounding air (which also follows newton's first law of inertia - body in motion tends to remain in motion, etc).

Answer 2

i think its like neutons law: for every action, there is an equal and opposite reaction.
so when the car stops (action) you lurch forwards (reaction)
the same is true when you accelerate and are pushed back