# Homework Help: Momentum and force

1. Nov 15, 2015

### Saanchi

a car of mass 600 kg travels with a speed of 10m/s and a scooter of mass 80kg with 50m/s

Which will require more force to stop
(1) in same time
2) in same distance
Give reasons

Ans :
((2) car because being lighter it will acquire more momentum as momentum depends on product of force and time duration. Thus lighter body will acquire more momentum
Am I right ? Or have I got it wrong?

Thanks

2. Nov 15, 2015

### honlin

Nope. revise back the defination of momentum. Sometimes we can use mathematics approach to answer the question. Especially for this type of question where the given the quantities are not the same and cant be compared directly.

3. Nov 15, 2015

### honlin

Btw, the momentum approach is for part 1, it will be easier to solve the 2nd question with another way

4. Nov 15, 2015

### Saanchi

yes I know that momentum is product of mass and velocity
But change in momentum is dependant on force and time duration..

5. Nov 15, 2015

### honlin

For the first question, why dont u calculate the momentum for each vehicles? What is the relationship between momentum, force and time?

6. Nov 15, 2015

### honlin

after calculating the momentum for each vehicles,by relating it to force and time, you will have 2 equations. Since they will stop at the same time, which one is easier to stop? The vehicle with larger momentum or the lower one? You can link those equations together since both equations have the same constant.

7. Nov 15, 2015

### honlin

For the second part, since they will stop at the same distance, how can we relate distance, force, mass and velocity together? Think along this line and u will get the answer surely. The answer in part b will not be the same as in part a

8. Nov 15, 2015

### Saanchi

Part 1) car
2) scooter
Am I right

9. Nov 15, 2015

### Ray Vickson

No, that is against the PF rules. You need to do the work yourself, or ask for hints, not solutions.