# A car with a mass of 1800 kg slows from 42 km/h [E] to 28 km/h [E].

• CabalGroupie

## Homework Statement

A car with a mass of 1800 kg slows from 42 km/h [E] to 28 km/h [E]. The impulse from the brakes is?

I know its a simple question but I was hoping if I could get a walkthrough. I keep getting the answer 2.5 x 10^4 N*s [W] and the answer is 7.0 x 10^3 N*s

p=pf-pi

## The Attempt at a Solution

(1800)(28[E])-(1800)(42[E])=50400[E]-75600[E]
=25200[W]
=2.5 x 10^4 N*s [W]

Hello CabalGroupie,

Welcome to Physics Forums!

## Homework Statement

A car with a mass of 1800 kg slows from 42 km/h [E] to 28 km/h [E]. The impulse from the brakes is?

I know its a simple question but I was hoping if I could get a walkthrough. I keep getting the answer 2.5 x 10^4 N*s [W] and the answer is 7.0 x 10^3 N*s

p=pf-pi

## The Attempt at a Solution

(1800)(28[E])-(1800)(42[E])=50400[E]-75600[E]
=25200[W]
=2.5 x 10^4 N*s [W]

Don't forget to convert your velocities from kilometers per hour to meters per second.

Gahh thank you! I feel so incredibly stupid right now that question bothered me way more then it should have