Calculating Frequency for Induction Motors with Given Horsepower and Pole Count

[onceinalifetim]

Hello

I'm doing a question in induction motor now.

formula for Induced torque is Pgap / Ws.

i have found the Pgap, but in order to find Ws, i need frequency to find ns..
so my question is, how to find frequency with only given 10hp and four pole

 

[NascentOxygen]

The rated speed of an induction motor is typically within 5% of that motor's synchronous speed. http://www.engineeringtoolbox.com/speed-electrical-motors-d_738.html

Broadly speaking, in engineering, an answer correct to within 10% is generally acceptable. There are always exceptions to rules of thumb, but I can't see the question under discusion being one of them.