Final answer:
The kinetic energy of the car increases because the velocity increases, as kinetic energy is directly proportional to the square of the velocity. The mass of the car does not change during acceleration, and mechanical energy increases due to the transformation into kinetic energy when velocity increases.
Step-by-step explanation:
When a driver pushes his foot on the gas pedal and the car accelerates, the kinetic energy of the car increases due to an increase in velocity. This relationship is explained as kinetic energy being directly proportional to the square of velocity, meaning that when the velocity of the car doubles, the kinetic energy quadruples, resulting in increased motion. An important note here is that a car's mass remains constant while accelerating; it does not increase as velocity increases.
Thus, the correct statement is: The kinetic energy of the car increases because the velocity increases. Kinetic energy is calculated using the formula KE = 1/2 mv2, where 'm' is mass and 'v' is velocity. As velocity increases, the square of the velocity increases even more significantly, greatly impacting the kinetic energy.
In conclusion, option (a) mechanical energy of the system increases due to the transformation into kinetic energy, provided there are no significant losses such as friction. During acceleration, the car gains kinetic energy, not potential energy, as its velocity increases.