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posted by  liscivious on 5/29/2008 12:54:13 AM  |  status: Closed  

physics-mechanics

Course Textbook Chapter Problem
General Physics Physics (3rd) by Walker 9 N/A
Question Details:

The first stage of a space vehicle consumed fuel and oxidizer at the rate of 2.25 multiplied by 104 kg/s, with an exhaust speed of 3.00 multiplied by 103 m/s.

(a) Calculate the thrust produced by these engines.
N
(b) Find the acceleration of the vehicle just as it lifted off the launch pad on the Earth if the vehicle's initial mass was 3.00 multiplied by 106 kg. [Note: You must include the force of gravity to solve part (b).]
m/s2 upward
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posted by Varmonds on 5/29/2008 3:42:58 AM  |  status: Live
Asker's Rating: Lifesaver   
liscivious's comment:
"nice"
Response Details:
given
The first stage of a space vehicle consumed fuel and oxidizer at
the rate of (Δm/Δt) =  2.25 multiplied by 104 kg/s
exhaust speed v = 3.0*103m/s
a)
 the thrust produced by these engines is = (Δm/Δt) * v
                                                            = 2.25*104 *3.0*103
                                                             = 67.5*106N
b)
    the initial net force acting on the rocket is
       Fnet = thrust - mg
   here
  g = 9.8m/s2
  mass m = 3.0*106kg
    so mg = 3.0*106 *9.8
              = 29.4 *106N
      so Fnet  =   67.5*106N - 29.4 *106N
                   = 38.1*106N
   the acceleration of the vehicle is
        a = Fnet/m
          a = 38.1*106N / 3.0*106kg
          a  = 12.7m/s2 
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