text: the various forces 
  which act on the aircraft during takeoff roll. 
  The powerplant thrust is the principal force to 
  provide the acceleration and, for minimum 
  takeoff ,distance, the output thrust should be 
  at a maximum. Lift and drag are produced as 
  soon as the airplane has speed and the values 
  of lift and drag depend on the angle of attack 
  and dynamic .pressure. Rolling friction results 
  when there is a normal force on the wheels 
  and the friction 
  force is the product of the 
  normal force and the coefficient of rolling 
  The normal force pressing the wheels 
  friction. 
  against the runway surface is the net of weight 
  and lift while the rolling friction coefficient is 
  a function of the tire type and runway surface 
  texture. 
  
  The general relationship of velocity, accel- 
  eration, and distance for uniformly accelerated 
  motion is illustrated by figure 2.31. 
  In this 
  illustration., acceleration distance is shown as 
  a function of velocity for various values of 
  acceleration. 
  
  TAKEOFF PERFORMANCE. The mini- 
  mum takeoff distance is of primary interest in 
  the operation of any aircraft because it defines 