Question

A Boeing 707 jet aircraft has a takeoff mass of 1.2 x 105 kg. Each of its four engines has a net thrust of 75 kN. Calculate the acceleration and the length of the runway needed to become airborne if the takeoff speed is 73 m/s. (Neglect any frictional forces and air resistance)

Answer 1

$v^2-u^2=2as\\\\u=0,\ v=73\ m/sec,\ \ s=? ,\ \ \ a=\frac{F}{m}=\frac{4*75*1000N}{1.2*10^5kg}=2.5 m/sec^2\\\\s=\frac{73^2}{2*2.5}=1065.80\ meters$