Kinetic energy?

A 1500 kg car is traveling 30 m/s along a horizontal road when the brakes are applied. The car skids to a stop in 4 s. How much kinetic energy ( in J) does the car lose in this time ? Physics Question ?? HELP

Public Comments

1. I HATE PHYSICS!!!!!!!!!!!!!!
2. No idea. I have always regretted not taking physics.
3. Isn't that potential energy? I have no idea, my brother is learning that but he doesn't learn during class. Sorry no idea, ask in askjeeves.com?
4. geeze just ask your teacher if you are having problems with your homework.....
5. If the car comes to a complete stop, then it should have lost all of its kinetic energy. So as the car was moving, it had 1/2 m v^2 (1/2)(1500)(30)^2 = 675,000 J The time seems to be in there just to throw you off, if the question is asking how much KE the car lost (it ends up with none).
6. I think it's(1500 x 30)-4 but I'm not sure.
7. KE=1/2mv^2 KE=1/2(1500)(30^2) KE=675000J its asking how much KE is lost, so if its at stop then it lost all its energy so KE=0 at the end of the 4s i think the time is there to get people confused
8. Kinetic energy is the energy that a body possesses as a result of its motion. It is formally defined as the work needed to accelerate a body from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. Negative work of the same magnitude would be required to return the body to a state of rest from that velocity.
9. Not sure if this is in joules or not Ke=W*V2/64.4 Ke=3306.93*98.43 squared/64.4 Ke=3306.93*9688.4649/64.4 Ke=32039075.23/64.4 Ke=497501.1682 The amount of time is meaningless because the vehicle skidded to a stop and there fore lost all of its kinetic energy during the four seconds. Note: I had to change m/s into f/s and kg into lbs.