Question

An airplaine in taking off from a field makes a run of 2300ft and leaves the ground in 15.0s from the start. (a) what its acceleration assumed constant? (b) with what speed does it leaves the ground?

Answer 1

(a)

$$d=v_0t+at^2/2, \; v_0=0$$

$$a=2d/t^2=2*2300/15.0^2=20.4\:\rm ft/s^2$$

(b)

$$d=\frac{v_f+v_0}{2}t, \; v_0=0$$

$$v_f=2d/t=2*2300/15.0=307\rm \: ft/s$$