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DYNAMICS - CASE STUDY

    Introduction


Problem Diagram

 

The pilot of an F-16 must get his plane in the air in less than 30 seconds to defend against enemy aircraft. Can he do it?

What is known:

  • The mass of the F-16 is m = 14,600 kg.
  • The liftoff speed is vLO = 45.7 m/s.
  • For the first 5 seconds of the takeoff roll, the magnitude of the thrust of the jet increases from 22,250 N to 111,250 N at a constant rate. After 5 seconds, the thrust is constant at 111,250 N.
  • The takeoff roll is a straight line.
  • All friction forces can be neglected.
     

  Questions

   

What is the velocity of the F-16 after 5 seconds?

How long does it take for the F-16 to reach the velocity required for liftoff?

     
    Approach

   
  • Express the thrust of the F-16 as a function of time.
  • Determine the relationship between the external force acting on the plane and the change in velocity.
  • Use the principle of impulse and momentum.
     
   
 
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