# Kinetic Energy problem... i think..

by nlsed
Tags: energy, kinetic
 P: 10 1. The problem statement, all variables and given/known data What takes more energy? Accelerating a car from 10-20m/s or from 20-30m/s? Why? 2. Relevant equations 3. The attempt at a solution Since KE = 1/2mv^2, I suppose the higher the velocity is the more kinetic energy the car will have, but I have no clue how to solve this problem.
 HW Helper P: 5,346 Won't the bigger change in kinetic energy require the greater energy? You know that conservation of energy thing? Plug in the numbers.
 P: 473 then change in kinetic energy equals the work done, which one requires more work?
P: 10

## Kinetic Energy problem... i think..

so is this right? since m is constant it is just 1kg

1/2mv2
1/2(1kg)(10m/s)2 = 50 joules
1/2(1kg)(20m/s)2 = 200 joules
1/2(1kg)(30m/s)2 = 450 joules

KE for (10-20m/s) = 150 joules
KE for (20-30m/s) = 250 joules

So accelerating from 20-30m/s requires 100 more joules of energy?
HW Helper
P: 5,346
 Quote by nlsed So accelerating from 20-30m/s requires 100 more joules of energy?
That should do it.
 P: 10 Thank you very much!!!

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