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

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Homework Help Overview

The discussion revolves around a physics problem related to power usage in a small single-engine airplane. The airplane's engine has a power output of 76 kW, and it is gaining altitude at a rate of 2.8 m/s while having a mass of 660 kg. Participants are exploring how to calculate the fraction of engine power being used for climbing.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants initially attempt to calculate the fraction of power used for climbing using mass and velocity but express uncertainty about their results. Some question the omission of gravitational force in their calculations, while others suggest incorporating it into their power calculations.

Discussion Status

There is an ongoing exploration of different approaches to the problem. Participants have provided guidance on incorporating gravitational force into the power calculations, and multiple interpretations of the problem are being discussed.

Contextual Notes

Participants are grappling with the correct application of physics principles, particularly the role of gravity in calculating power. There is a sense of confusion regarding the initial setup of the problem and the assumptions made in the calculations.

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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