Question

The potential energy and kinetic energy of a helicopter flying at a height of 400m are in ratio of 5 is to 2 what is the velocity of the helicopter

Answer 1

Potential energy (P) = mgh
Kinetic energy (K) = 0.5mv²

According to question
P / K = 5/2
K = 0.4P
0.5mv² = 0.4 × mgh
mv² = 0.8 mgh
Divide both sides by “m”
v² = 0.8gh
v = √(0.8 gh)
v = √(0.8 × 9.8 m/s² × 400 m)
v = √(3136 m²/s²)
v = 56 m/s

Velocity of helicopter is 56 m/s

Answer 2

Let mass of the helicopter be = x.
Let the velocity be=v.
Height=400m.g=10m/s^2
Kinetic energy =1/2 mv^2.
Potential energy=mgh.
mgh/(1/2mv^2)=5/2
4000m*2*2=5mv^2.
v^2=16000/5
v^2=3200
v=√3200
v=56.57 m/s(approx.).