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Homework Help: Back to the fundementals. Mechanics, simple problem

  1. Oct 10, 2014 #1
    1. The problem statement, all variables and given/known data
    s(t)=At-Bt^2+Ct^3,where A,B,C is know constants.
    What is the path,velocity and accelartion after 2s from begining of motion.

    2. Relevant equations

    3. The attempt at a solution

    But where i get confuzed is when im asked to calculate v,s,a after 2s.
    If i would calculate s(t=2s),v(t=2s),a(t=2s) it would be at time 2s not after 2s,am i right? so how to calculate after 2s?
  2. jcsd
  3. Oct 10, 2014 #2


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    Homework Helper

    Imagine that you start the stopwatch at the instant the motion starts. The time t is the reading on the stopwatch. When 2 s elapsed after the start, the reading is 2 s. Just substitute t= 2s.

  4. Oct 10, 2014 #3
    This is semantics. They meant "at" 2 s.
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