GCSE Physics - Internal Energy and Specific Heat Capacity #28

Summary

This video explores the relationship between an object's internal energy and temperature through the concept of specific heat capacity. It explains that internal energy consists of potential and kinetic energy, with the latter being crucial for temperature changes. The script introduces specific heat capacity as the energy required to raise a substance's temperature by one degree Celsius and demonstrates its application with a practical example. The video concludes with a calculation to find the final temperature of water after energy transfer, highlighting the importance of insulation in real-life experiments.

Takeaways

• 🔥 Internal energy is the total energy stored by the particles in a substance or system, often divided into potential and kinetic energy.
• 🌡 Kinetic energy, which is related to the movement of particles, is the key component affecting temperature when a substance is heated.
• 🌡 Temperature is a measure of the average internal energy of a substance, with higher internal energy correlating to higher temperature.
• 🔄 Materials vary in the amount of energy required to change their temperature, which is described by specific heat capacity.
• 💧 Water has a high specific heat capacity, requiring 4,200 joules to raise the temperature of 1 kg by 1 degree Celsius.
• 🌀 Mercury has a much lower specific heat capacity, needing only 139 joules to heat 1 kg by 1 degree Celsius.
• ⚖ The specific heat capacity can be defined as the energy needed to raise the temperature of 1 kg of a substance by 1 degree or the energy released when it cools.
• 📚 The change in internal energy can be calculated using the formula: ΔE = m * c * ΔT, where ΔE is the change in internal energy, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.
• 📈 An example in the script calculates the final temperature of 800 grams of water after 20 kilojoules of energy transfer, using the specific heat capacity of water.
• 🔢 The calculation involves converting units to kilograms and joules, and then applying the formula to find a temperature change of 5.95 degrees Celsius.
• ⚠ Real-world energy transfer may not result in the exact temperature increase due to energy loss to the surroundings, especially in an open system without insulation.

Q & A

What is internal energy?

Internal energy is the total energy stored by the particles making up a substance or system.

How is internal energy divided?

Internal energy is often considered to be made up of two parts: potential energy stores and kinetic energy stores.

Which part of internal energy is related to temperature?

The kinetic energy store is related to temperature, as it involves the movement energy of the particles.

What happens when a substance is heated?

When a substance is heated, energy is transferred to the kinetic energy store of its particles, increasing their internal energy and thereby raising the temperature.

What is specific heat capacity?

Specific heat capacity is the amount of energy needed to raise the temperature of one kilogram of a substance by one degree Celsius.

How does the specific heat capacity of water compare to mercury?

Water has a specific heat capacity of 4200 joules per kilogram per degree Celsius, whereas mercury requires only 139 joules per kilogram per degree Celsius.

What is the formula for calculating the change in internal energy?

The change in internal energy is equal to the mass times the specific heat capacity of the substance times the change in temperature.

How can you find the change in temperature from the change in internal energy?

To find the change in temperature, divide the change in internal energy by the product of mass and specific heat capacity.

What is the specific heat capacity of water?

The specific heat capacity of water is 4200 joules per kilogram per degree Celsius.

What would be the final temperature of 800 grams of water initially at 20 degrees Celsius after 20 kilojoules of energy has been transferred to it?

The final temperature would be 25.95 degrees Celsius, or 26.0 degrees if rounded to three significant figures.

Outlines

00:00

🔥 Understanding Internal Energy and Temperature

This paragraph introduces the concept of internal energy and its relationship with temperature. It explains that internal energy is the total energy stored by particles in a substance, which includes potential and kinetic energy. The focus is on kinetic energy, which is directly related to temperature, as heating a substance increases its internal energy and thus its temperature. The paragraph also introduces the term 'specific heat capacity,' which quantifies the energy needed to change the temperature of a substance by one degree Celsius. Examples are given to illustrate the varying specific heat capacities of water and mercury.

🌡️ Specific Heat Capacity and Temperature Change Calculation

This paragraph delves into the specific heat capacity, explaining it as the energy required to raise the temperature of one kilogram of a substance by one degree Celsius. It also describes the equation that relates the change in internal energy to mass, specific heat capacity, and temperature change. A practical example is provided to calculate the final temperature of 800 grams of water after it has absorbed 20 kilojoules of energy. The process involves converting units to kilograms and kilojoules, applying the formula, and interpreting the result, which is a temperature increase of 5.95 degrees Celsius, leading to a final temperature of approximately 26.0 degrees Celsius.

Keywords

💡Internal Energy

Internal energy refers to the total energy stored by the particles that make up a substance or system. It is a fundamental concept in the video, as it is the energy that gets transferred to particles when a substance is heated, increasing their kinetic energy and thus their temperature. The video emphasizes that internal energy is composed of potential and kinetic energy, with the latter being directly related to temperature changes.

💡Potential Energy

Potential energy is a type of stored energy, such as gravitational or elastic potential, which is not directly related to temperature. In the context of the video, it is mentioned that potential energy can be largely ignored when discussing the relationship between internal energy and temperature, as it does not play a significant role in the heating process being examined.

💡Kinetic Energy

Kinetic energy is the energy of movement possessed by the particles of a substance. It is central to the video's theme, as it is the type of energy that increases when a substance is heated, leading to an increase in the substance's internal energy and temperature. The video illustrates this by explaining that heating a substance transfers energy to the kinetic energy store of its particles.

💡Temperature

Temperature is a measure of the average internal energy of a substance. The video explains that as a substance's internal energy increases due to the addition of heat, its temperature also rises, making temperature a key indicator of a substance's internal energy state.

💡Specific Heat Capacity

Specific heat capacity is the amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius. It is a critical concept in the video, used to quantify how different materials respond to heat. For example, water has a high specific heat capacity, requiring more energy to change its temperature compared to mercury.

💡Joules

Joules are the unit of energy in the International System of Units (SI). The video uses joules to express the specific heat capacity of substances and to calculate the energy transferred to or from a substance during heating or cooling.

💡Kilogram

Kilogram is the SI unit of mass. In the context of the video, it is used to describe the mass of substances when calculating the energy required to change their temperature, as seen in the formula for change in internal energy.

💡Celsius

Celsius is a unit of temperature measurement. The video uses Celsius to describe the temperature change of substances, particularly when discussing the specific heat capacity and the formula for calculating temperature changes.

💡Change in Internal Energy

The change in internal energy is the difference in energy before and after a substance is heated or cooled. The video explains that this change is equal to the product of mass, specific heat capacity, and change in temperature, which is a fundamental equation used to understand thermal processes.

💡Energy Transfer

Energy transfer refers to the movement of energy from one place to another. In the video, it is shown that when a substance is heated, energy is transferred to its particles, increasing their kinetic energy and, consequently, the substance's internal energy and temperature.

💡Significant Figures

Significant figures are the digits in a number that carry meaningful information about its precision. The video mentions rounding the final temperature to three significant figures, which is a common practice in scientific calculations to ensure the accuracy of the results.

Highlights

The video explores the relationship between an object's internal energy and its temperature using the concept of specific heat capacity.

Internal energy is the total energy stored by the particles of a substance, often divided into potential and kinetic energy.

Potential energy stores like gravitational and elastic potential are not temperature-related and are ignored in this context.

Kinetic energy is the movement energy of particles and is directly related to temperature changes when a substance is heated.

Temperature is a measure of the average internal energy of a substance.

Different materials require varying amounts of energy to increase their temperature, as illustrated by water and mercury examples.

Specific heat capacity is defined as the energy needed to raise one kilo of a substance's temperature by one degree Celsius.

The specific heat capacity can also represent the energy released when a substance cools by one degree Celsius.

An equation is presented to calculate the change in internal energy based on mass, specific heat capacity, and temperature change.

An example problem is provided to find the final temperature of water after energy transfer, using its specific heat capacity.

The calculation involves dividing energy by mass times specific heat capacity to find the change in temperature.

Units must be correctly converted for accurate calculations, such as grams to kilos and kilojoules to joules.

The final temperature of the water is calculated to be 25.95 degrees Celsius after energy transfer.

The video notes that in real-life scenarios, some energy is typically lost to the surroundings as heat.

For classroom experiments, it is recommended to use a lid and insulate the setup to minimize energy loss.

The video concludes with an invitation for viewers to like, subscribe, and stay tuned for future content.

Transcripts

in today's video we're going to look at

how the internal energy of an object

relates to its temperature

using the concept of specific heat

capacity

now the first thing we need to do is

take a look at a few terms

internal energy is the total energy

that's stored by the particles making up

a substance or system

and we often talk about it as if it's

made up of two parts

the potential energy stores

and the kinetic energy stools

the potential energy stores are things

like gravitational and elastic potential

but they're not really related to

temperature so we can pretty much ignore

them in this video

on the other hand kinetic energy is the

movement energy of the particles

and this is the one that's important

whenever you heat up a substance it

transfers energy to the kinetic energy

store of all the particles

and so increases their internal energy

we measure this as an increase in

temperature

because temperature is just a measure of

the average internal energy of a

substance

so the more internal energy that a

substance has

the higher its temperature will be

however some materials require a lot

more energy to increase their

temperature than others

for example water requires four thousand

two hundred joules of energy

to warm one kilo a bit by one degree

celsius

whereas one kilo of mercury can be

heated by one degree celsius with only

139 joules of energy

we call these numbers the specific heat

capacity

which is the amount of energy needed to

raise the temperature of one kilo of a

substance by one degree celsius

it can also be thought of as the amount

of energy released as that substance

cools

so each time our kilo of water cools by

one degree celsius

it will give out 4200 joules of energy

to the surroundings

we can put this idea into an equation

where the change in internal energy

is equal to the mass

times the specific heat capacity for

that particular substance

times the change in temperature

where the triangle's meaning change

and the zero the line through it being a

theta sign which here means temperature

to see how this works let's try a

question

find the final temperature of 800 grams

of water

at an initial temperature of 20 degrees

celsius after 20 kilojoules of energy

has been transferred to it

the specific heat capacity of water is 4

200 joules per kilo per degree

well in order to find the final

temperature what we're really looking

for is the change in temperature

so to get that term by itself we need to

divide both sides by mse

giving us energy divided by mass times

specific heat capacity

equals change in temperature

next we make sure all of our units are

correct

so change 800 grams to 0.8 kilos

and change 20 kilojoules to 20 000

joules

and then plug these values into the

equation

so overall we get a temperature change

of

5.95 degrees

and if we add that onto our original 20

degrees

the final temperature would be

25.95 degrees

or 26.0 degrees if we round it to three

significant figures which we generally

should

one thing to point out here is that in

real life the temperature probably

wouldn't actually increase this much

because some of the energy would be lost

the surroundings

mostly in the form of heat

so if you're going to do this experiment

in a classroom you'd want to make sure

they used a lid and then you insulated

it well

anyway that's everything for this video

so if you liked it then do give it a

like and subscribe and we'll see you

soon