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    • Thread Starter

    ok ive been wondering about this for a while. 0 / 0 ??

    what is the answer?


    when you take the equation of motion - v = u + at
    and rearrange it to: t = (v-u)/a

    if you are travelling at a constant velocity then a = 0 and v-u = 0
    so you get: t = 0/0.

    so what would time be in this case?
    • PS Helper

    PS Helper
    if you are travelling at constant velocity, then the final velocity = intial velocity irrespectve of the duration of motion. therefore, t doesnt have a solution

    There would be no need to solve for t in this case. The only place you'd need to find t is if the car was travelling at a constant speed v over a displacement s.

    (Original post by Devp93)
    t = (v-u)/a
    Ultimately, the most important thing to consider with mechanics is the question of "what is the physical interpretation of my formula?"

    In this circumstance, if you take a look at what you've written down you'll quickly realise that the physical meaning is this:

    How long does it take me to get from initial velocity, u, to final velocity, v, assuming I am accelerating with acceleration, a?

    Evidently, the answer is that it takes no time at all, i.e. the answer is zero.

    So what does this mean mathematically? It means that the numerator is "more zero" (strange concept I know) than the denominator. This is a concept that you will consider more deeply when you do more pure mathematics - the idea that some infinite functions will reach a limit "faster" than other functions which reach the same limit. In the situation you've described, the mathematical understanding is that the fact that the final velocity is the same as the initial velocity, overrides the fact that it takes zero time to get from one speed to the other
    • Thread Starter

    cool that helps a lot thanks
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