The equation F=−vex(dm/dt) for the thrust on a rocket, can also be applied to an airplane propeller. In fact, there are two contributions to the thrus

geduiwelh

geduiwelh

Answered question

2021-04-11

The equation F=−vex(dm/dt) for the thrust on a rocket, can also be applied to an airplane propeller. In fact, there are two contributions to the thrust: one positive and one negative. The positive contribution comes from air pushed backward, away from the propeller (so dm/dt<0), at a speed vex relative to the propeller. The negative contribution comes from this same quantity of air flowing into the front of the propeller (so dm/dt>0) at speed v, equal to the speed of the airplane through the air.
For a Cessna 182 (a single-engine airplane) flying at 130 km/h, 150 kg of air flows through the propeller each second and the propeller develops a net thrust of 1300 N. Determine the speed increase (in km/h) that the propeller imparts to the air.

Answer & Explanation

Tuthornt

Tuthornt

Skilled2021-04-13Added 107 answers

Using the thrust equation provided: F=v dm/dt 
Given dm/dt=150kg/s 
net thrust F=1300 N 
Thus, the speed v=F/dm/dt 
v=1300/150=8.66 m/s 
It has now been converted to kmph 
speed v=31.2 kmph

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