just checking

My method was correct right?, sorry to post again I just wanted to double check that I had the setup right:
A 8000N car is traveling 12 m/s along a horizntal road when the brakes are applied. The car skids to a stop in 4.0s. How much kinetic energy does the car have.

my work:

W= 8000N/9.18m/s
mass= 815.49 kg
Kinetic energy= (1/2mv^2-1/2mv^2)
kinetic energy=1/2 (815.49)(0)^2 - 1/2 (815.49)(12 m/s)^2 =5.0 X 10^4 J

One more question:
A sled weighs 3000N. It is pulled on level ground by a dog team. The coefficient for kinetic friction is 0.03. How much work is done by the dog team in pulling the sled 500m at a constant speed?

My work:
Friction coefficient is F=coefficient *N= (.03 * 3000N)= 90N
W= F*d= 90N * 500m=45000J
is the solving method good

Method is correct. I don't agree with your calculation of 5.0E4. I assume the value for g was a typo.

yes on the sled work.

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asked by Jenny

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