Answer: 9
Explanation:
The kinetic energy of a car is given by
[tex]E_k = \frac{1}{2}mv^2[/tex]
where
m is the mass of the car
v is its speed
In this case, the kinetic energy of the car moving at 20 mph is
[tex]K_1 = \frac{1}{2}m(20)^2[/tex]
While the kinetic energy of the car moving at 60 mph is (assuming same mass m)
[tex]K_2 = \frac{1}{2}m(60)^2[/tex]
The ratio between the two kinetic energies is:
[tex]\frac{K_2}{K_1}=\frac{\frac{1}{2}m(60)^2}{\frac{1}{2}m(20)^2}=\frac{60^2}{20^2}=(\frac{60}{20})^2=3^2=9[/tex]
So, the faster car has a kinetic energy which is 9 times more than the slower car.
