What fraction of the engine power is being used for the place to fly

AI Thread Summary
The discussion revolves around calculating the fraction of engine power used by a small single-engine airplane to climb. Initially, the user attempted to calculate this using only the climbing velocity, resulting in an incorrect figure of 2.4%. After realizing the need to account for gravitational force, the correct formula incorporates both the climbing speed and gravitational acceleration. The final calculation yields that approximately 23.8% of the engine's 76 kW power is utilized for climbing. The conversation highlights the importance of including gravitational effects in power calculations for accurate results.
cantgetno
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Homework Statement


When its engine of power 76 kW is generating full power, a small single-engine airplane with mass 660 kg gains altitude at a rate of 2.8 m/s.
What fraction of the engine power is being used to make the airplane climb?

Homework Equations


total power=76x10^3 W
mass=660 kg
dx/dt=velocity=2.8 m/s

Power=mass x velocity

The Attempt at a Solution


(660x2.8)/(76x10^3) x 100 = 2.4% but this is wrong and I am not sure where I've gone wrong
 
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cantgetno said:

Homework Statement


When its engine of power 76 kW is generating full power, a small single-engine airplane with mass 660 kg gains altitude at a rate of 2.8 m/s.
What fraction of the engine power is being used to make the airplane climb?

Homework Equations


total power=76x10^3 W
mass=660 kg
dx/dt=velocity=2.8 m/s

Power=mass x velocity

The Attempt at a Solution


(660x2.8)/(76x10^3) x 100 = 2.4% but this is wrong and I am not sure where I've gone wrong

There's no gravity?
 


oh of course

660(2.8+9.8)/(76x10^3) x 100 =10.9%

is that it?
 


cantgetno said:
oh of course

660(2.8+9.8)/(76x10^3) x 100 =10.9%

is that it?

No. Because Power is Work / time = Force * distance / time

In this case it is P = m*g *v
 


OK i get what you mean

so its:

660x2.8x9.8 / 76x10^3 x 100 = 23.8

thank you lots
 


cantgetno said:
OK i get what you mean

so its:

660x2.8x9.8 / 76x10^3 x 100 = 23.8

thank you lots

There you go.

Cheers.
 
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