EK physics

[yellowjellybean]

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The chemical potential energy in gasoline is converted to kinetic energy in cars. If a car accelerates from zero to 60km/h, compared to the energy necessary to increase the velocity of the car from zero to 30 km/h, the energy necessary to increase the velocity of the car from 30 to 60 km is:

A: 3 times as great.

I understand that if you double the velocity, you increase the KE by 4, BUT then EK does this 4-1= 3 thing that I don't understand. Where does the 1 come from?

Thank you

 

[Silo004]

(1/2)mv^2=KE right?

60^2-30^2=2700

30^2=900

2700/900=3