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Magazine Chapter 5: Problem 113
How many joules of energy are in a kilowatt-hour?
Short Answer
Expert verified
1 kilowatt-hour equals 3,600,000 joules.
Step by step solution
01
Understanding Units
To solve this problem, we first need to understand the units involved. One kilowatt-hour (kWh) is a unit of energy, representing the amount of energy consumed by a one-kilowatt appliance running for one hour.
02
Converting Kilowatts to Watts
A kilowatt (kW) is 1,000 watts (W). Therefore, 1 kilowatt-hour is equivalent to 1,000 watt-hours.
03
Converting Hours to Seconds
There are 60 minutes in an hour and 60 seconds in a minute. Thus, there are 60 x 60 = 3,600 seconds in one hour.
04
Calculating Energy in Joules
Energy in joules can be calculated by multiplying power in watts by time in seconds. Therefore, 1 kilowatt-hour is equivalent to 1,000 watts x 3,600 seconds.
05
Final Calculation
Perform the multiplication: 1,000 watts x 3,600 seconds = 3,600,000 joules. Therefore, 1 kilowatt-hour equals 3,600,000 joules.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Joules
The joule is a fundamental unit of energy in the metric system, named after the British physicist James Prescott Joule. It's used to measure energy, work, or the amount of heat. When we talk about energy in joules, we're referring to the amount of energy required to perform a certain amount of work.
For example, one joule is the energy transferred when one newton of force is applied over a distance of one meter. This is why joules are often used as a universal unit across various branches of physics and engineering.
For example, one joule is the energy transferred when one newton of force is applied over a distance of one meter. This is why joules are often used as a universal unit across various branches of physics and engineering.
- One joule is equal to one watt-second.
- It serves as the standard unit for electric energy calculations.
- Joules are crucial when discussing energy transformations and conversions.
Decoding Kilowatt-hour
The kilowatt-hour (kWh) is an energy unit widely used to measure electricity consumption. This unit helps us to quantify the energy usage of electrical devices, typically for billing purposes.
Essentially, one kilowatt-hour is the energy consumed by a 1,000-watt appliance running for an hour. It's a handy way to understand how much electricity is used over time in our homes and businesses.
Here's a simple breakdown:
Essentially, one kilowatt-hour is the energy consumed by a 1,000-watt appliance running for an hour. It's a handy way to understand how much electricity is used over time in our homes and businesses.
Here's a simple breakdown:
- 1 kilowatt-hour = 1,000 watt-hours
- It's a larger unit designed to make big numbers more manageable for reporting and billing.
- Electric bills usually reflect usage in kilowatt-hours.
The Concept of Power
Power is the rate at which energy is used or transferred. It can be thought of as how fast work is done or energy is transformed. The standard unit of power is the watt (W), named after James Watt, who improved the steam engine.
A higher power rating means more energy is used in less time. When we see power ratings on electrical devices, they're usually in watts or kilowatts, indicating the energy consumption rate.
A higher power rating means more energy is used in less time. When we see power ratings on electrical devices, they're usually in watts or kilowatts, indicating the energy consumption rate.
- Power = Energy / Time
- In electrical terms, power equals the voltage times the current.
- 1 watt = 1 joule per second, showing the direct relationship between energy and time.
Understanding Watts
Watts are the unit of measurement for power, reflecting how fast energy is produced or consumed. When you see a device rated in watts, it tells you how much power it consumes instantaneously.
For instance, a 60-watt light bulb consumes 60 watts of power when turned on.
For instance, a 60-watt light bulb consumes 60 watts of power when turned on.
- 1 watt equals 1 joule per second.
- It helps in calculating energy usage and efficiency.
- Devices with higher wattage consume more energy over a given time frame.
