A watt is a measure of power (the rate of energy change) equal to 1 J / s. (a) Calculate the nu

step 1 Solving party of this problem, so we all know that 1 watt is equal to 1 jule per second and 1 ki

A watt is a measure of power (the rate of energy change)...

A watt is a measure of power (the rate of energy change) equal to $1 \mathrm{~J} / \mathrm{s}$. (a) Calculate the number of joules in a kilowatt-hour. (b) An adult person radiates heat to the surroundings at about the same rate as a 100 -watt electric incandescent lightbulb. What is the total amount of energy in kcal radiated to the surroundings by an adult in 24 hours?

Key Concepts

Unit Conversion and Dimensional Analysis

Unit conversion involves using appropriate conversion factors to change a measurement from one unit to another while maintaining the physical meaning of the quantity. Dimensional analysis is the systematic method used to check and carry out these conversions properly, ensuring that the final answer has the correct dimensions and units. This technique is key in verifying the consistency and correctness of physical and engineering calculations.

Joule to Kilocalorie Conversion

The conversion from joules to kilocalories involves a conversion factor where one kilocalorie is approximately equal to 4184 joules. This concept is crucial when comparing energy values across different contexts, particularly when energy output or intake is expressed in nutritional or thermal terms rather than in joules.

Power

Power is the rate at which energy is transferred or converted. It is typically measured in watts, with one watt defined as one joule per second. This concept is fundamental in understanding how quickly energy is used or transformed in any physical system.

Energy and its Units

Energy is the capacity to do work, and it can be expressed in various units such as joules, kilowatt-hours, and kilocalories. Joules are the International System (SI) unit of energy, while kilowatt-hours are commonly used in the context of electrical energy consumption, and kilocalories often refer to the energy content in food. Recognizing these units and their relationships is essential for converting energy values from one form to another.

Kilowatt-Hour to Joule Conversion

A kilowatt-hour is a unit of energy that represents the consumption of 1000 watts over the period of one hour. Since one hour consists of 3600 seconds, a kilowatt-hour can be converted to joules by multiplying 1000 watts by 3600 seconds, yielding 3.6 million joules. This conversion is a practical example of how power and time product relates to energy.

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