Question

4. A jet engine is moving an airplane forward at a speed of 900 km/hr. If the thrust of the engine is 1 x 105 N, what is the power developed by the engine?

a. 5 MW
b. 10 MW
c. 25 MW
d. 50 MW

Answer 1

Power is a measure of energy input/output per unit time, or Joules per second. Mechanical power can also relate force (thrust) and velocity by:
\[ P=F*v\]
The only problem is that you velocity is given in km/h, which are not standard units (Watts are in J/s). So convert km/h to m/s:
\[900 km/h \div 3.6 = 250m/s\]
\[250m/s*10^5N=25*10⁶W\]
or 25 megawatts.

Answer 2

Thanks so much!!!

Answer 3

My pleasure!