• Question: if i were to drive a car of a speed at 100 mph and i took the key out of the ignition bit would the car instantly stop or would it keep going and slow down until it can no longer keep moving?

    Asked by randomberries to Daphne, Darren, Katherine on 22 Mar 2012.
    • Photo: Darren Logan

      Darren Logan answered on 22 Mar 2012:

      Most cars lock the key in the ignition when it is turned on, so you can’t remove it. But assuming you could, if you were travelling at 100 mph the car would be in gear. Once you turn the engine off, the gears would slow down the car pretty quickly, but not instantly. If you took it out of gear and turned it off, then you would still slow down but much slower.

    • Photo: Daphne Ng

      Daphne Ng answered on 22 Mar 2012:

      It will not stop instantly. This is because of inertia which is the tendency of an object to resist change in its motion. Hence, a moving car will remain moving until another force acts on it. In this case, friction between the ground and the tires will eventually cause the car to stop but it will take some time.