# Each of the four engines on a DC-8 airplane develops 7500 horse power (hp), when thecruising speed is 240 m/s. How much thrust does each engine produce under thesecircumstances?

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### 1 Answer

By definition the mechanical work done by a force `F` that moves a mass along a distance `d` is

`W =F**d`

where`**` is the scalar product of the vectors representing force `F` and distance `d` . ` `` `Now we consider the vectors parallel and divide the work to the time interval in which it was done to find the power

`P = (F*d)/t = F*d/t =F*v`

where `v` is the speed of the mass on which is applied the force.

Thus for one engine the thrust is (1HP =745.7 W)

`F = P/v =(7500*745.7)/240 =23303.13 N`

**The thrust of one engine is 23303.13 N**

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