Quick Kinetic Energy question - only confirmation of answer needed.

AI Thread Summary
The discussion revolves around calculating the change in kinetic energy of a 2000kg car as it accelerates from 30km/h to 60km/h. The kinetic energy at 30km/h is calculated to be 69,389J, while at 60km/h it is 278,890J, resulting in a change of 209,501J. Participants confirm that the increase in kinetic energy is due to the car's increase in velocity, attributing the source of energy gain to the car's engine. The conversation concludes with a consensus on the calculations and the source of energy. Overall, the calculations and explanations provided are validated.
Griffy11
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Hi guys,

Calculate the change in kinetic energy of a car of mass 2000kg if it changes its velocity from 30km/h to 60km/h

KE=1/2mv^2

So, to find the change in KE, subtract its KE when it was going 30km/h from when it was going 60km/h.

At 30km/h:
KE=1/2mv^2
KE=1/2*200*8.33^2
KE=69389J

At 60km/h:
KE=1/2mv^2
KE=1/2*2000*16.7^2
KE=278890J

So change in KE is 209501-69389
= 209501J

Is that correct, or am I doing it totally wrong?

Also - "explain the source of the energy gain" - would that just be an increase in velocity?
 
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Yes that is correct. The source would be what is producing motion in the car in the first place. So this would be the?
 
The driving force/friction between the tires and the road?
 
Well I'd just say it is the engine.
 
Alright great, thanks for your help! :)
 

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