Question

A helicopter takes off vertically. It starts from rest at time t=0, and has a constant
upwards acceleration of 0.40 m/s2. The mass of the helicopter is 14 000 kg. The
acceleration of free fall is 10 m/s2
.

Answer 1

The speed of the helicopter at time 20 s will be

$$v(t)=v_0+at,\\ v(20)=0+0.40\cdot20=8.0\text{ m/s}.$$

The resultant force acting on the helicopter:

$$F=ma=14000\cdot0.40=5600\text{ N}.$$