Horsepower

Definition

Horsepower is a unit of power that measures the rate at which work is done. It is commonly used to quantify the power output of engines and motors.

5 Must Know Facts For Your Next Test

1. One horsepower is equivalent to 746 watts.
2. Horsepower was originally defined by James Watt in the 18th century to compare steam engine output with the power of draft horses.
3. In physics, power is calculated as work done over time, and horsepower provides a practical way to express this for mechanical systems.
4. The formula to convert watts to horsepower is $\text{HP} = \frac{P(\text{W})}{746}$ where $P$ stands for power in watts.
5. Horsepower can also be expressed in terms of torque and rotational speed using the formula $\text{HP} = \frac{T \times N}{5252}$ where $T$ is torque in pound-feet and $N$ is rotational speed in RPM.

Review Questions

• How many watts are equivalent to one horsepower?
• Who originally defined the term 'horsepower'?
• What formula would you use to convert torque and rotational speed into horsepower?

Related terms

Power:

The rate at which work is done or energy is transferred, measured in watts (W) in the SI system.

Watt:

A unit of power in the International System of Units (SI) equal to one joule per second.

Torque:

A measure of the rotational force applied on an object, typically measured in pound-feet or newton-meters.