Term 2 · Class 6 Science · Chapter 1

Samacheer Class 6 Science - Heat

27 textbook Q&A27 verifiedFree Content

Chapter-wise textbook exercise answers for Heat with validation-aware solutions.

Answers marked verified were checked during generation against the chapter context and source question text.
Sections in this chapter
I. Choose the correct answer: 4II. Fill in the Blanks 1III. True or False. If False, give the correct answer. 1IV. Give reasons for the following 3VI. Analogy 1VII. Give Very Short Answer: 3VIII. Give Short Answer: 2IX. Answer in detail: 1X. Questions based on Higher Order Thinking Skills 3I. Choose the right answer: 4V. Give reasons for the following: 1VI. Very Short Answer: 3
Your Progress - Chapter 10% complete
1I. Choose the correct answer:4 questions
Q.1When an object is heated, the molecules that make up the objectv
  1. A. begin to move faster
  2. B. lose energy
  3. C. become heavier
  4. D. become lighter
Solution

(a) begin to move faster

Answer:

(a) begin to move faster

Q.2The unit of heat isv
  1. A. newton
  2. B. joule
  3. C. volt
  4. D. Celsius
Solution

(b) joule
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Answer:

(b) joule
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Q.3One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will bev
  1. A. 80°C
  2. B. More than 50°C but less than 80°C
  3. C. 20°C
  4. D. around 40°C
Solution

(d) around 40° C

Answer:

(d) around 40° C

Q.4An iron ball at 50°C is dropped in a mug containing water at 50°C. The heat willv
  1. A. flow from iron ball to water.
  2. B. not flow from iron ball to water or from water to iron ball.
  3. C. flow from water to iron ball.
  4. D. increase the temperature of both.
Solution

(b) not flow from iron ball to water or from water to iron ball.

Answer:

(b) not flow from iron ball to water or from water to iron ball.

2II. Fill in the Blanks1 questions
Q.G1Heat flows from a ……….. body to a ………… body. The hotness of the object is determined by its ……….. The SI unit of temperature is ………… Solids ……….. on heating and ………… on cooling. Two bodies are said to be in the state of thermal ………… if there is no transfer of heat taking place.v
Solution

hot, cold
temperature
Kelvin
expand, contract
equilibrium
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Answer:

hot, cold
temperature
Kelvin
expand, contract
equilibrium
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

3III. True or False. If False, give the correct answer.1 questions
Q.G2Heat is a kind of energy that flows from a hot body to a cold body. Steam is formed when heat is released from water. Thermal expansion is always a nuisance. Borosilicate glass do not expand much on being heated. The unit of heat and temperature are the same.v
Solution

True
False – Steam is formed when the heat is absorbed from the water.
False – Thermal expansion is always not a nuisance.
True
False – Unit of heat and temperature are different.

Answer:

True
False – Steam is formed when the heat is absorbed from the water.
False – Thermal expansion is always not a nuisance.
True
False – Unit of heat and temperature are different.

4IV. Give reasons for the following3 questions
Q.1An ordinary glass bottle cracks when boiling water is poured into it, but a borosilicate glass bottle does not.v
Solution

The reason is that the borosilicate glass does not expand much on being heated and therefore they do not crack.

Answer:

The reason is that the borosilicate glass does not expand much on being heated and therefore they do not crack.

Q.2The electric wire which sag in summer become straight in winter.v
Solution

During summer thermal expansion takes place in electric wire.
In winter it contracts so it becomes straight.

Answer:

During summer thermal expansion takes place in electric wire.
In winter it contracts so it becomes straight.

Q.3Rivet is heated before fixing in the hole to join two metal plates.v
Solution

When we heat rivet expansion takes place and becomes soft.
One end of the rivet is hammered to form a new head.
When cooled, the rivet will contract and hold tightly.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Answer:

When we heat rivet expansion takes place and becomes soft.
One end of the rivet is hammered to form a new head.
When cooled, the rivet will contract and hold tightly.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

5VI. Analogy1 questions
Q.G3Heat: Joule :: Temperature : ……… Ice cube : 0°C :: Boiling water : ……….. Total Kinetic Energy of molecules: Heat:: Average Kinetic Energy : …………….v
Solution

Kelvin
100° C
Temperature

Answer:

Kelvin
100° C
Temperature

6VII. Give Very Short Answer:3 questions
Q.1Make a list of electrical types of equipment at home from which we get heat.v
Solution

Water heater, Iron box, Electric kettle, Micro oven.

Answer:

Water heater, Iron box, Electric kettle, Micro oven.

Q.3What is thermal expansion?v
Solution

The expansion of a substance on heating is called thermal expansion.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Answer:

The expansion of a substance on heating is called thermal expansion.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Q.4What do you understand by thermal equilibrium?v
Solution

When two objects in thermal contact, no longer affect each other’s temperature, there exists Thermal equilibrium.

Answer:

When two objects in thermal contact, no longer affect each other’s temperature, there exists Thermal equilibrium.

7VIII. Give Short Answer:2 questions
Q.1What difference do you think heating the solid will make in their molecules?v
Solution

When we heat solids the vibrations and movement of molecules will increase.
The temperature of the object increases.
The distance between molecules will increase.

Answer:

When we heat solids the vibrations and movement of molecules will increase.
The temperature of the object increases.
The distance between molecules will increase.

Q.2Distinguish between heat and temperature.v
Solution

Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat 2

Answer:

Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat 2

8IX. Answer in detail:1 questions
Q.1Explain thermal expansion with suitable examples.v
Solution

Thermal expansion: The expansion of a substance on heating is called, the thermal expansion of that substance.
Fitting the iron rim on the wooden wheel:
The diameter of the iron ring is slightly less than that of the wooden wheel.
So, it cannot be easily slipped on from the rim of a wooden wheel.
The iron ring is, therefore, first heated to a higher temperature so that it expands in size and the hot ring is then easily slipped over to the rim of the wooden wheel.
Coldwater is now poured on the iron ring so that it contracts in size and holds the wooden wheel tightly.
Rivetting:
Rivets are used to join two steel plates together.
Hot rivet is driven through the hole in the plates.
One end of the rivet is hammered to form a new rivet head.
When cooled, the rivet will contract and hold the two plates tightly together.
Cracking of a thick glass tumbler:
Glass is a poor conductor of heat.
When hot liquid is poured into the tumbler, the inner surface of the tumbler becomes hot and expands while the outer surface remains at room temperature and does not expand.
Due to this unequal expansion, the tumbler cracks.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Answer:

Thermal expansion: The expansion of a substance on heating is called, the thermal expansion of that substance.
Fitting the iron rim on the wooden wheel:
The diameter of the iron ring is slightly less than that of the wooden wheel.
So, it cannot be easily slipped on from the rim of a wooden wheel.
The iron ring is, therefore, first heated to a higher temperature so that it expands in size and the hot ring is then easily slipped over to the rim of the wooden wheel.
Coldwater is now poured on the iron ring so that it contracts in size and holds the wooden wheel tightly.
Rivetting:
Rivets are used to join two steel plates together.
Hot rivet is driven through the hole in the plates.
One end of the rivet is hammered to form a new rivet head.
When cooled, the rivet will contract and hold the two plates tightly together.
Cracking of a thick glass tumbler:
Glass is a poor conductor of heat.
When hot liquid is poured into the tumbler, the inner surface of the tumbler becomes hot and expands while the outer surface remains at room temperature and does not expand.
Due to this unequal expansion, the tumbler cracks.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

9X. Questions based on Higher Order Thinking Skills3 questions
Q.1When a window is accidentally left open on a winter night, will you feel uncomfortable because the cold is getting in, or because the heat is escaping from the room?v
Solution

When a window is left open on a winter night I will feel uncomfortable because the heat is escaping from the room.
The heat will transfer from high temperature to low temperature.
During winter cold air enters the room, so room temperature will decrease.

Answer:

When a window is left open on a winter night I will feel uncomfortable because the heat is escaping from the room.
The heat will transfer from high temperature to low temperature.
During winter cold air enters the room, so room temperature will decrease.

Q.2Suppose your normal body temperature was lower than what it is. How would the sensation of hot and cold change?v
Solution

When our body temperature is lower than normal temperature, We feel hot from the surrounding.
Because the surrounding temperature will be high compare to our body.

Answer:

When our body temperature is lower than normal temperature, We feel hot from the surrounding.
Because the surrounding temperature will be high compare to our body.

Q.3If you heat a circular disk with a hole, what change do you expect in the diameter of the hole? Remember that the effect of heating increases the separation between any pair of particles.v
Solution

Many of us “expect” that the diameter of the hole will decrease because the circular disk is free to expand in all directions as well. Note that expansion of metal due to heating is not like gas spreading out wherever space is available. The correct way to think about it is as follows: Hole size is irrelevant in this case. So we can think that hole is very large.
If we carve a hole so large that its radius is slightly less than that of the circular disk itself, then we will have a ring. It is obvious that the radius of the ring will increase, as atoms have more energy so their oscillation amplitude will increase. As the diameter of the ring increases, the diameter of the hole will also increase.
For example, if you want to insert one hallow pipe inside another hollow pipe of the same diameter, just heat anyone and insert the second one into the heated pipe. This explains the answer in an easy way. So it says that diameter will increase with increasing temperature.

Answer:

Many of us “expect” that the diameter of the hole will decrease because the circular disk is free to expand in all directions as well. Note that expansion of metal due to heating is not like gas spreading out wherever space is available. The correct way to think about it is as follows: Hole size is irrelevant in this case. So we can think that hole is very large.
If we carve a hole so large that its radius is slightly less than that of the circular disk itself, then we will have a ring. It is obvious that the radius of the ring will increase, as atoms have more energy so their oscillation amplitude will increase. As the diameter of the ring increases, the diameter of the hole will also increase.
For example, if you want to insert one hallow pipe inside another hollow pipe of the same diameter, just heat anyone and insert the second one into the heated pipe. This explains the answer in an easy way. So it says that diameter will increase with increasing temperature.

10I. Choose the right answer:4 questions
Q.1When an electric current is passing through the conductor …………… energy is produced.v
  1. A. Electric
  2. B. Heat
  3. C. Chemical
  4. D. Kinetic energy
Solution

(b) Heat

Answer:

(b) Heat

Q.2One day in 1922, the air temperature was measured at 59°C in the shade in Libya ________v
  1. A. America
  2. B. Africa
  3. C. Antarctica
  4. D. Europe
Solution

(b) Africa
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Answer:

(b) Africa
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Q.3The temperature of boiling water is …………..v
  1. A. 0° C
  2. B. 32° C
  3. C. 100° C
  4. D. 110° C
Solution

(c) 100°C

Answer:

(c) 100°C

Q.4The temperature determines the direction flow of _______v
  1. A. heat energy
  2. B. kinetic energy
  3. C. potential energy
  4. D. light energy
Solution

(a) heat energy

Answer:

(a) heat energy

11V. Give reasons for the following:1 questions
Q.1Gaps are left in between rails while laying a railway track.v
Solution

Reason: During summer thermal expansion takes place.

Answer:

Reason: During summer thermal expansion takes place.

12VI. Very Short Answer:3 questions
Q.1What are the sources of heat?v
Solution

The main source of heat is Sun.
Other sources are combustion, friction and electricity.

Answer:

The main source of heat is Sun.
Other sources are combustion, friction and electricity.

Q.2Define – heat.v
Solution

Heat is an energy that raises the temperature of a thing by causing the molecules in that thing to move faster.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Answer:

Heat is an energy that raises the temperature of a thing by causing the molecules in that thing to move faster.
Samacheer Kalvi 6th Science Guide Term 2 Chapter 1 Heat

Q.3How will you identify two objects are said to be in thermal equilibrium?v
Solution

Two objects in thermal contact have same temperature they are said to be in thermal equilibrium.

Answer:

Two objects in thermal contact have same temperature they are said to be in thermal equilibrium.