1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Back to the fundementals. Mechanics, simple problem

  1. Oct 10, 2014 #1
    1. The problem statement, all variables and given/known data
    hi,guys!
    Problem:
    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
    So
    v(t)=s'(t)
    a(t)=s''(t)

    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

    ehild

    User Avatar
    Homework Helper
    Gold Member

    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.

    ehild
     
  4. Oct 10, 2014 #3
    This is semantics. They meant "at" 2 s.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Back to the fundementals. Mechanics, simple problem
Loading...