Since the car is going uphill and the force of gravity is pulling straight down, there is a component of this force that pulls opposite to the speed causing the car to slow down. As it rises, there is an increase in gravity. The higher it goes, the more powerful it becomes.
Of course, the same thing can happen in the past. If you let an object move along a path, the gravitational force will decrease and the kinetic energy will increase. So you still need brakes or some form of friction to keep the car from sliding backwards. Many of these escape routes are made of gravel that is too soft to produce enough impact that a stationary vehicle will stop.
Down on the ground
Manual transmissions, or stick-shift cars, aren’t as popular as automatics—but they still exist. With a stick shift, the driver has to manually shift from one gear to another while increasing speed. But they can also use the same method to reduce the speed of the car.
Let’s say he is in fourth gear traveling at 40 kilometers per hour. If they shift into third gear and take their foot off the pedal, the car will downshift. They don’t have to touch the brake pedal, meaning the car’s lights won’t turn on even if it’s slowing down. Of course, if the driver needs to stop at a short distance, this reduction will not be enough, and he will have to use traditional brakes.
How does this work? I’m just giving you a cursory description of the internal combustion engine, but that’s all we need to understand the downside. An engine provides power by adding fuel to the compressed air in the cylinders. When the fuel is ignited, the gas expands and pushes the pistons down. The pistons moving up and down rotate the crankshaft, which (with several other connections) turns the wheels. Boom, you’re driving! To do this, you need oil, a fuel burner, and compression.
What if you remove the spark and oil? If the wheels work with the engine through the transmission, there is gas pressure in the cylinders. This gas combination increases the engine’s rotational resistance and can be used to decelerate the vehicle. (Of course, you still need friction between the tires and the road.)
In terms of energy, we still need an increase in energy to match the decrease in kinetic energy. It should come as no surprise that you experience an increase in thermal energy. When gas is compressed, it is heated—and there is your energy.
What if there was a way to slow down a car and reduce its kinetic energy, and save that energy? Well, that’s exactly what happens in regenerative braking.
It all starts with an electric motor, which is basically a wire winding around a pole around a magnet. When electricity flows through the block, there is a connection between the current and the magnet, and this causes the sound to move around the pole. This also works in the background. If you move a wire in front of a magnet, it will create an electric current. This means that an electric car and an electric generator are the same thing. For the engine, you give it current and move things. Like a generator, you rotate a shaft and you get electrical energy.