Question

A boy is riding a bike. He applies the brakes and slows down. How has his momentum changed and why?

Answer 1

Just a slightly different more scientific view of this question
as I know my physics teacher would not approve of the previous answer.

Momentum is the product of the mass and velocity of an object
Momentum P=mv= units kg.m/s

M=mass
v=velocity

So if velocity decreases (mass remaining constant) momentum will decrease.

If you think about it it’s more difficult to stop a train than a car because a car has lesser momentum than the train

Answer 2

Answer
I'm Thinking it's the amount of force Applied to the Bicycle

Step-by-step explanation:

For Example, Let's say I was Riding a Bicycle and I Applied Full force My Bicycle Would Probably slowdown in fact I know it would because I've Rode on a bicycle before and as soon as I applied force it slowed down A bit.

I Hope This Helped Have a Nice Day!