• Question: how does petrol fuel vehicles?

    Asked by 649hspc32 to Jamie, Simon, Will on 26 Jun 2015.
    • Photo: William Scott-Jackson

      William Scott-Jackson answered on 26 Jun 2015:

      Cars are powered by what you can an internal combustion engine. This means that the petrol is ignited by the spark plug in your car and the chemical energy released from the burning of petrol is used to move the various parts of the car to make it drive.

      The trouble with burning fuel is that we create other emissions such as carbon dioxide, carbon monoxide and nitrogen. Our planet struggles to cope with turning it all back into oxygen. This is part of what’s causing climate change. It’s up to engineers to help find new ways to power cars that don’t emit as much or not emit anything at all.

    • Photo: Jamie Johnston

      Jamie Johnston answered on 26 Jun 2015:


      The engine in your car is actually quite a simple machine, because it is difficult to create rotational movement, the engine turns up and down movements into a rotational movement.

      To create an up and down movement we have a piston in a cylinder, we then need to create pressure against the piston to make it move down, the simplest way to do this is to create a small explosion. This is where the petrol comes in, petrol is highly flammable and when we ignite it in a small space (like a cylinder) the explosion happens and the pressure created pushes the piston, the gas released from the explosion then escapes out of the exhaust and the cycle repeats.

      Here’s an animation that shows the machine process, it goes into a little more detail but gives a good idea:

    • Photo: Simon Marchant

      Simon Marchant answered on 26 Jun 2015:

      I have nothing to add that these excellent gentlemen haven’t already said, I just wanted to say that petrol is made of ancient plant and animal stuff from the time of the dinosaurs, which has been crushed by rocks for millenia. So cars run on DINOSAURS! That’s all, I’m out.