Question

Starting from rest, a 2500 kg helicopter accelerates straight up at a constant 1.7 m/s2. What is the helicopter's height at the moment its blades are providing an upward force of 29 kN? The helicopter can be modeled as a 2.6-m-diameter sphere.

How do you start this question? Does it include gravity?

Answer 1

let g = 9.8 m/s^2

weight = 2500 * 9.8 = 24,500 N

Thrust - weight - drag = m a

29,000 - 24,500 - drag = 2500 (1.7)

drag = 250 N at this speed and thrust

Now I do not know what your class has done about drag of a sphere. However what is needed is the speed at which the drag of this 1.3 meter radius sphere is 250 Newtons in air.
then v = 1.7 t and h = (1/2)1.7 t^2

Answer 2

No, we have not covered Thrust. Thank you for your help.