Watts = Volts X Amps so Amps = Watts Divided by Volts.
Almost. Watts = Volts x Amps x Power Factor. Power Factor takes into account phase shift and harmonics.
This is purely an electrical factor and NOT a mechanical factor. Watts is electrical power , not mechanical power. In the case of electric motors, the power indicated by watts is the power drawn from the wall socket not the power output produced at the motor shaft. I dont remember the story but somehow some body a long time ago decided that 1 hp = 746 Watts.
No. The Watt is the metric unit for power, whether electrical or mechanical. Horsepower is the Imperial or US Customary unit of power.
Metric: One Watt = one Newton-meter per second. (Volts and Amps are defined in terms of mechanical units)
Imperial: One horsepower = 550 foot-pound per second.
Plug in the conversion factors for meters to feet and Newtons to pounds and you get 746 W/hp.
So a very inefficient electrical motor can draw a lot of amps and not produce as much mechanical power as a very efficient electrical motor drawing the same wattage.
Bottom line is that the current method of determining mechanical power by applying 746 Watts = 1 HP is really quite useless.
A NEMA rated motor (US) has its shaft power rated in horsepower. An IEC rated motor (Europe) has it's shaft power rated in Watts. By convention, the conversion factor used for this rating is actually the rounded value of 750 Watts/horsepower.
A 1.5 kW IEC motor is the same as a 2 hp NEMA motor. Same motor, different label.
So yes, output power = input Volts x Amps x efficiency x power factor, making input Amps only a rough indication of output power.