Hpower and watts?

Question

How many horsepower is a 350 W lightbulb?
How many watts is a 120 hp car?

Answer 1

Electrical horsepower = 0.746 kwatts = 746 watts
Mechanical horsepower = 0.7457 kwatts = 745.7 watts

A 350 watt lightbulb = 350/746 = 0.4692 horsepower

A 120 hp car = 120*0.745 kWatts = 89.5 kW

Answer 2

I am only answering because there is some misinformation above. A horsepower is defined as 550 ft-lb/sec, in metric terms this is 745.7 watts (a watt is defined as a kg-m^2/sec^3) You can verify this conversion by using all the conversions to get from one to the other.

It makes no difference whether it's electrical, kinetic, potential or heat energy, it is all energy and all the same. We have a convention in the US of using hp for mechanical work, BTUs for heat and watts for electrical power. It is only a convention. In the metric system (SI) the power of an engine is expressed in watts not hp.

For your original question. Just use the conversion that 1 hp = 745.7 watts

Answer 3

There is no good direct correlation as one, (hp) has to do with the amount of work that can be done by a horse pulling a load a specific distance. The other is a measure of the amount of electrical energy used to light a bulb. In the first case, you have kinetic energy that has the capability of moving a given load a given distance at a given speed. In the other, you have a given energy usage determined by the product of the EMF and the consumed current.