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!

Launching from Mars

  1. Oct 25, 2008 #1
    1. The problem statement, all variables and given/known data
    The Radius of Mars is R_m
    its mass is m

    The radius of Mars (from the center to just above the atmosphere) is R_m and its mass is m. An object is launched from just above the atmosphere of mars.

    A) what is the object's initial velocity if its final velocity is V_f

    2. Relevant equations

    a=(v^2)/R <--wat v is this?
    W=deltaKE

    3. The attempt at a solution

    i dont know how to start

    im thinking i need to calculate the gravity from mars?
    but if all im given is mass and radius
    how do i calculate it?

    i need to find the amount of work done by mars right?
     
    Last edited: Oct 25, 2008
  2. jcsd
  3. Oct 25, 2008 #2
    I think you need to use Newtons universal gravity law....

    F=(GM1M2)R^2

    This means that the force is equal to the constant G (6.67X10^-11) multiped by both masses, all of this divided by the distance between them squared.

    this will get you the Force.

    So now you have force, you know that Fnet=ma, so the acceleration will be {(Gm1m2)/R^2}/m

    finally, Vf^2-Vo^2=2a(x), so you simply solve using the above equation as a, and they just say to use Vo i believe
    I dont think this is a problem you shoudl get numbers for, it seems like a concept that you just want to work through with different equations and not really use numbers.

    This is just from what I understand.

    Good luck!
     
  4. Oct 26, 2008 #3
    im solving for Vo

    the object is launched from above the atmosphere

    im given the distance between object and mars (R_m)
    and I'm given the weight of mars (m)

    and I'm given Vf of the object

    so what I did (but I did not get a good answer)

    was use

    F=Gm1m2/r^2

    m1 = object
    m2 = mars
    r=distance from mars and object

    so the F equals

    F= Gm1m2/(R_m)^2

    and then I think I'm suppose this formua

    total W = deltaKE

    F*d = .5m1vf^2 - .5m1vo^2

    but how do I find d?

    I think this is right

    how do I use

    vf^2-vo^2 = 2a (x) <--whats x ?
     
  5. Oct 26, 2008 #4
    With what you have you won't be able to find work and finding energy is also not going to work out. I can't help if you dont supply numbers, I solved it simply with the units, plugging the numbers in should have yielded the answer.

    From what I can understand by your explanation that is anyway, it doesn't seem like work is in anyway involved.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Launching from Mars
Loading...