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Kinetic Energy problem i think

  • Thread starter nlsed
  • Start date
  • #1
10
0

Homework Statement



What takes more energy? Accelerating a car from 10-20m/s or from 20-30m/s? Why?

Homework Equations





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.
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
3,090
4
Won't the bigger change in kinetic energy require the greater energy?
You know that conservation of energy thing?

Plug in the numbers.
 
  • #3
459
1
then change in kinetic energy equals the work done, which one requires more work?
 
  • #4
10
0
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?
 
Last edited:
  • #5
LowlyPion
Homework Helper
3,090
4
So accelerating from 20-30m/s requires 100 more joules of energy?
That should do it.
 
  • #6
10
0
Thank you very much!!! :!!)
 

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