What’s the difference between Heat and Temperature? | Class 7th Physics |

Summary

In this educational video, Scientist Radha Krishna (SRK) and his assistant Benny explore the concepts of heat and temperature. Through a mix of virtual world explanations and lab demonstrations, they highlight the difference between heat (the total energy in a substance) and temperature (the measure of average molecular motion). Key topics include calibrating thermometers, understanding thermal equilibrium, and the role of body temperature regulation. The video also touches on practical examples like refrigerators and air conditioners to show how heat can flow from cooler to warmer environments.

Takeaways

• 🌡️ Temperature measures the degree of hotness or coldness of an object.
• 🧪 Temperature is measured using a thermometer, with the SI unit being Kelvin (K).
• 🔥 Heat is the total amount of energy in a substance, while temperature is the average energy of molecular motion.
• 💡 Heat flows from an object with a higher temperature to one with a lower temperature until thermal equilibrium is reached.
• 🌍 The greater the mass of a substance, the more heat is required to raise its temperature.
• 🔬 Heat and temperature are related, but they are not the same—temperature indicates average molecular motion, while heat represents total energy.
• 🧊 A simple experiment to calibrate a thermometer involves measuring temperatures at the melting point of ice and the boiling point of water.
• 👩‍🔬 Objects at around 54-55°C can cause pain, so it’s important to be aware of body temperatures and external heat sources.
• 🛠️ Systems like refrigerators and air conditioners can transfer heat from cooler to warmer environments using electricity.
• 🩺 The human body has its own internal temperature regulation system, using mechanisms like sweating to maintain balance.

Q & A

What is the definition of temperature?

Temperature is defined as the degree of hotness and coldness of an object.

What instrument is used to measure temperature?

Temperature is measured using an instrument called a thermometer.

What is the SI unit of temperature, and how is it related to Celsius?

The SI unit of temperature is Kelvin (K), and 273.15 K is equal to 0 degrees Celsius.

How is a thermometer calibrated?

A thermometer is calibrated by placing it in ice to mark the melting point at 0 degrees Celsius (lower fixed point), and then placing it in boiling water to mark the boiling point at 100 degrees Celsius (upper fixed point). The space between is divided into 100 equal divisions.

What is the difference between heat and temperature?

Heat is the total amount of energy in a substance, while temperature is the average energy of the molecules in motion within that substance.

Why do molecules in water at 70°C vibrate more than those at 20°C?

The molecules at 70°C vibrate more because they have more average energy due to the higher temperature compared to the molecules at 20°C.

How does heat flow between two objects with different temperatures?

Heat flows from the body with a higher temperature to the body with a lower temperature until both objects reach thermal equilibrium.

Why does it take more heat to raise the temperature of a larger quantity of water compared to a smaller quantity?

A larger quantity of water has more mass, and thus, it requires more heat energy to raise its temperature compared to a smaller quantity.

What happens to the body when it is exposed to high temperatures?

When exposed to high temperatures, the body sweats, and blood vessels in the skin expand to dissipate excess heat. Sweat evaporation helps cool the body, which maintains a stable temperature around 36°C.

Can heat flow from a cooler object to a warmer one? How does this happen?

Yes, heat can flow from a cooler object to a warmer one with the help of external energy, such as electricity in appliances like refrigerators and air conditioners. These systems transfer heat from a cooler interior environment to a warmer exterior.