Define power. What is the relation of its SI unit with horsepower?

Power is defined as the rate at which work is done or the rate at which energy is transferred or converted. It measures how quickly energy is used or produced. In simpler terms, power tells us how fast a task is being completed in terms of energy.

Mathematically, power can be expressed as:

P=W/t

Where:

  • P is power,
  • W is work (or energy transferred),
  • t is the time taken to do the work.

In the International System of Units (SI), the unit of power is the watt (W).

SI Unit of Power: Watt (W)

The watt (W) is the SI unit of power and is defined as one joule of energy transferred or used per second:

1 Watt=1 Joule/second

So, a power of 1 watt means that 1 joule of energy is used in 1 second.

Power and Horsepower

Horsepower (hp) is a non-SI unit used to measure power, primarily in the context of engines or mechanical work. It was originally introduced by engineer James Watt to compare the output of steam engines with the power of draft horses.

The relation between watts and horsepower is as follows:

1 horsepower (hp)=746 watts (W)

Conversion between Horsepower and Watts

  • To convert horsepower to watts:

    Power (in watts)=Power (in horsepower)×746

  • To convert watts to horsepower:
  • Power (in horsepower)=Power (in watts)/746

Example

  • If a car engine produces 100 horsepower, the equivalent power in watts would be:

    100 hp×746 W/hp=74,600 W

  • If a device consumes 1,500 watts of power, the power in horsepower would be:

    1,500 W/746≈2.01 hp

Related Questions:

  1. Define work and its unit. Describe the conditions for maximum and minimum work.
  2. What is kinetic energy? Derive its expression using graphical analysis.
  3. What is potential energy? What are its different types? Show that gravitational potential energy is equal to the product of mass ‘m’, gravitational field strength ‘g’, and height ‘h’.
  4. What is meant by energy conversion and energy conservation?
  5. Describe how useful energy may be obtained from natural resources.
  6. Differentiate between renewable and non-renewable energy sources with examples. Write down advantages and disadvantages of each in reference to their availability and environmental impact.
  7. Describe the processes by which energy is converted from one form to another with reference to fossil fuel energy, hydroelectric generation, solar energy, nuclear energy, geothermal energy, wind energy, and biomass energy.
  8. Dynamics-1
  9. Dynamics-II
  10. Pressure and Deformation in Solids
  11. Work and Energy
  12. Density and Temperature
  13. Magnetism
  14. Work and Energy
  15. A car is moving with a constant speed along a straight road. Is there any work done on the car?
  16. Does the work done in raising a box up in a building depend upon how fast it is raised up? Through which path? To how much height?
  17. Work done on a body either speeds it up or slows it down. Keeping this in mind, explain how much work is done by centripetal force on an orbiting satellite?
  18. A car has kinetic energy ‘Eₖ’. By what factor would its kinetic energy change if its velocity is doubled?
  19. A bullet is fired from a gun, penetrates into a sand wall, and stops. Where does its kinetic energy go?
  20. How does using renewable energy sources contribute to reducing environmental impact compared to non-renewable sources?