The car drives evenly along a horizontal road, while: 1) kinetic changes, potential does not
The car drives evenly along a horizontal road, while: 1) kinetic changes, potential does not 2) potential changes, kinetic does not 3) both do not change 4) both change
For an electric car, the correct option is 3) both do not change.
The potential energy of a body is determined by the formula En = mgh, where m is the mass of the body, g is the acceleration of gravity, h is the height of the body’s position above the earth’s surface. In our example, none of these values change because the car is driving on a horizontal road. Consequently, the potential energy of the car remains unchanged.
The kinetic energy of a body is determined by the formula Ek = mv² / 2, – m is the mass of the body, v is the speed of movement of the body. In our example, neither the mass of the car, nor its speed change – the car moves uniformly, that is, at a constant speed. Hence,
kinetic energy also remains unchanged.
For a car using a gasoline or diesel engine, the correct option is 4) both change.
Because in this case, the mass of the car will decrease as it moves – the fuel burns in the engine, decreases in volume, the car becomes lighter by the amount of the weight of the burned fuel. Therefore, both the potential and kinetic energy of the vehicle
will decrease.