Brake power is defined as the power developed by an engine at the output shaft.
Mathematically can be expressed as,
[tex]W_b = \frac{2\pi NT}{60*1000}[/tex]
Where,
T = Torque
N = Number of Revolution
Torque is defined as the force by the distance applied, that is
[tex]T = F*d[/tex]
[tex]T = 9000*0.075[/tex]
[tex]T= 675N\cdot m[/tex]
The number of revolution would be
[tex]N = \frac{4200}{1.2}[/tex]
[tex]N = 3500rev/min[/tex]
Finally the Brake power would be:
[tex]W_b = \frac{2\pi NT}{60*1000}[/tex]
[tex]W_b = \frac{2\pi (675N\cdot m)(3500rev/min)}{60*1000}[/tex]
[tex]W_b = 247.4W[/tex]
