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Homework Help: Few Questions

  1. Dec 18, 2003 #1
    I got some questions that im blanking out on, if someone could tell me what forumla i use i would greatly appriciate it. 1 problem is about a space shuttle taking off that takes 200 seconds to reach its cruising speed of 11,200 m/s or 25 thousand mph, i have to find out at what rate it accelerates.
    2. to calculate a G I divide the acceleration by 10 correct?
    3. how do i calculate the weight of the rocket? I have the accelration, mass and force information of it i just need a formula
    4. how can i calculate the air friction? its got 20% more magnitiude then the weight of the rocket.
     
  2. jcsd
  3. Dec 18, 2003 #2
    This depends on whether the acceleration is uniform. If it is, then
    [tex]a=\frac{v_f-v_i}{\Delta t}[/tex]

    No. At the surface of the Earth g=9.8m/s2. To calculate g, you can divide the weight of an object by its mass.
    [tex]w=mg[/tex]
    Or you can plug in the Earth's radius into
    [tex]\frac{F}{m}=g=\frac{GM}{r^2}[/tex], where M is the mass of the Earth and G=6.67x10-11Nm2/kg2

    Again, w=mg.

    The weight is w=mg. The friction force is 20% greater than this, so
    Ff=(1.2)w

    Hope that helps!
     
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