Question

An aeroplane is flying high in sky at a constant speed.

1. What kind of equilibrium is shown by the aeroplane?
2. Name two sets of opposing forces acting on the aeroplane.
3. Are forces mentioned by you in equilibrium?

Answer 1

1. The aeroplane is in dynamic equilibrium because it is moving at a constant speed.
2. 1. The upward lift of the air and the downward weight of the aeroplane.
   2. The forward thrust produced by the engines and the backward air resistance (drag).
3. Yes. In steady flight, these opposing forces balance, so the resultant force is zero.