Maharashtra Board Class 8 Measurement and Effects of Heat

Maharashtra Board Class 8 Measurement and Effects of Heat , Textbook Exercises This page includes Fill in the Blanks, Questions and Answers, as well as Additional Questions and Answers for the chapter.

Whom should I pair with? Solution

                Group ‘A’  Group ‘B’

1. Temperature of a healthy human body b. 98.6 °F
2. Boiling point of water d. 212 °F
3. Room temperature a. 296 K
4. Freezing point of water c. 0°C

 

Who is telling the truth?

1. The temperature of a substance is measured in joule. False.
2. Heat flows from an object at higher temperature to an object at lower temperature. True.
3. The joule is the unit of heat. True.
4. Objects contract on heating. False.
5. Atoms of a solid are free. False.
6. The average kinetic energy of atoms in a hot object is less than the average kinetic energy of atoms in a cold object. False.

 

 You will find if you search.

a.A thermometer is used to measure ……………. [temperature]

b.The apparatus used to measure heat is called a ………… [calorimeter]

c.Temperature is the measure of the …………. kinetic energy of the atoms in a substance. [average]

d.The heat contained in a substance is the measure of the ………….kinetic energy of the atoms in the substance.[total]

 

What must be the temperature in Fahrenheit so that it will be twice its value in Celsius?

 Class 8 Measurement and Effects of Heat Additional QA

What is the unit of heat in the SI system?
Answer: c) Joule

 

What is geothermal energy?
Answer: b) Heat generated in the Earth’s center

 

Which element undergoes fission to produce a huge amount of heat in atomic energy projects?
Answer: b) Uranium

 

How is temperature different from heat?
Answer: a) Temperature is the total kinetic energy of atoms, while heat is the average kinetic energy.

 

What is the purpose of a clinical thermometer?
Answer: b) To measure body temperature

 

What is the unit of specific heat in the SI system?
Answer: c) Joule/(kg°C)

 

What does a calorimeter measure?
Answer: b) Heat content

 

Why is the inner vessel of a calorimeter made of copper?
Answer: a) It is a good conductor of heat.

Important Notes

I. Introduction

• Heat as a form of energy flow from high to low temperature objects.
• Temperature indicates the hotness or coldness of an object.
• Ice cream has a lower temperature than tea.

II. Various Effects of Heat

• Heat causes expansion and contraction in objects.
• Changes in the state of matter due to heat.
• SI unit of heat: Joule, CGS unit: calorie (1 cal = 4.18 J).

III. Sources of Heat

1. Sun: Nuclear fusion generates heat.
2. Earth: Geothermal energy from the high-temperature core.
3. Chemical energy: Burning fuels (wood, coal, petrol) produces heat.
4. Electrical Energy: Electricity powers devices generating heat.
5. Atomic energy: Fission of elements like uranium produces heat.
6. Air: Contains a significant amount of heat.

IV. Heat and Temperature

• The difference between heat and temperature.
• Temperature relates to the average kinetic energy of atoms.
• Heat is the total kinetic energy in a substance.
• Kinetic energies equalize when temperatures are equal.

V. Thermometer

• Clinical thermometer measures body temperature.
• Working principle: Expansion of liquid (alcohol) with temperature.
• Digital thermometers measure body heat directly.

VI. Calorimeter

• Measures heat content in an object.
• Inner and outer vessels prevent heat transfer.
• Hot or cold objects reach thermal equilibrium with water in the calorimeter.