1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Non-free-fall Acceleration Problem

  1. Feb 6, 2004 #1
    Sorry to have so many questions. Obviously, I am just not understanding the material. Our professor does not provide keys to problem sets he gives...

    The Question: If a rocket initially at rest accelerates at a rate of 50m/s/s for 1 minute, its speed will be: ??? I used d=1/2 at**2 (evidently the only formula I can remember, ha ha)...and got 3000 m/s. Correct?

    Thank you...
    "If I have seen less than others, it is because some giant's shoulders are always in the way."
  2. jcsd
  3. Feb 6, 2004 #2


    User Avatar
    Science Advisor
    Gold Member

    Your answer is correct, but it looks like you made it more complicated than necessary; if you write out exactly how you got the answer you did, we may be able to clear that up a little.

    This problem is exactly the same as your last problem. You are given a constant acceleration, a duration (time) for that constant acceleration, and an initial velocity (starts from rest; v0 = 0). Using v = v0 + at will give you the velocity at a given time.

    Here are the main kinematic equations that you should keep in mind for constant acceleration problems:

    [tex] v = v_0 + at [/tex]
    [tex] v^2 = v_0^2 + 2a\Delta x [/tex]
    [tex] x = x_0 + v_0 t + \frac{at^2}{2} [/tex]

    (They all come from the definitions of velocity, acceleration, and position, but that's only important if you're interested.)

    I hope those all look familiar. You should notice that the first equation gives velocity as a function of time, the second one gives velocity as a function of distance, and the last one gives position as a function of time. (They all are for constant acceleration.) Try to get a feel for what you should use based on what information is given in your problem and what is asked in the problem. Hope that clears things up a bit.
  4. Feb 6, 2004 #3
    Thx for Help

    Thank you for the help and especially for the advice about getting a feel for what it is I am being asked in the questions. I'm mortified that I did not recognize that it was basically the same problem as the one you answered before. And thank you for the kinematic equations, I will share them with my classmates. Thank you again.
  5. Feb 6, 2004 #4


    User Avatar
    Science Advisor
    Gold Member

    No problem at all. The more problems you do, the easier these will get; you may even start having fun doing them.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook