A red car and a blue car accelerate from rest to 100 km/h. The red car takes 9.1 s to accelerate and the blue car takes 10.3 s. The cars have the same mass. (a) Which car has the most kinetic energy? (a. 2) What is kinetic energy? (b) Which car has the most power? What assumption did you make when answering (a) and (b) ?

(a) Considering that they are travelling at the same velocity (100 km/h) and that they are of the same mass, they have equal kinetic energy. (a. 2) Kinetic energy is the form of energy associated with the movement of objects that have mass. (b) Power is work over time, and it can be calculated at any given moment by multiplying force times velocity. In this case, since the red car takes less time to accelerate to the same final velocity as the blue car, the force on the red car must be greater. While the cars are both accelerating, the red car must also have a greater velocity at any given moment since it is being acted upon by a greater force. Therefore, the value of force times velocity while the cars are accelerating is greater for the red car, and you can say that the red car has greater power. The critical assumption that I made in my reasoning is that acceleration is constant.