Samacheer Kalvi 6th Science Term 2 Solutions Chapter 1 Pdf
Tamilnadu Board Samacheer Kalvi 6th Science Term 2 Solutions Chapter 1: Tamilnadu State Board Solution Class 6 Science Term 2 Chapter 1 – Heat.
Samacheer Kalvi 6th Science Term 2 Solutions Chapter 1: Overview
Board |
Samacheer Kalvi |
Class |
6 |
Subject |
Science |
Chapter |
1 |
Chapter Name |
Heat |
Samacheer Kalvi 6th Science Term 2 Solutions Chapter 1 Pdf
I.) Choose the correct answer.
1.) When an object is heated, the Molecules that make up the object
a.) Begin to move faster
b.) Lose energy
c.) Become heavier
d.) Become lighter
Answer: Begin to move faster
Solution: The total kinetic energy present in particles of an object is called heat. This kinetic energy increases on heating the object. Hence, the molecules begins to move faster.
2.) The unit of heat is _________
a.) Newton
b.) Joule
c.) Volt
d.) Celsius
Answer: Joule
Solution: The SI unit of heat is joule. In addition, the unit calorie is also used in heat.
3.) One litre of water at 30°C is mixed With one litre of water at 50°C. The Temperature of the mixture will be
a.) 80°C
b.) More than 50°C but less than 80°C
c.) 20°C
d.) Around 40°C
Answer: Around 40°
Solution: When hot and cold water are mixed together, the cold water gains the heat from hot water and the hot water loses its heat thereby, keeping a balance in the temperature of the mixture. Here the temperature of mixture will be around 40°C.
4.) An iron ball at 50°C is dropped in a Mug containing water at 50°C. The Heat will
a.) Flow from iron ball to water.
b.) Not flow from iron ball to water or From water to iron ball.
c.) Flow from water to iron ball.
d.) Increase the temperature of both.
Answer: Not flow from iron ball to water or From water to iron ball.
Solution: As both the Substances water and iron having the same temperature i.e. 50°C , the heat will neither flow from iron ball to water nor from water to iron ball.
II.) Fill in the blanks
1.) Heat flows from a __higher temperature___ body To a __lower temperature___ body.
2.) The hotness of the object is determined By its ___temperature____
3.) The SI unit of temperature is _kelvin____
4.) Solids ____expand____ on heating And __contract_____ on cooling.
5.) Two bodies are said to be in the state Of thermal ___equilibrium____ if there is No transfer of heat taking place.
III.) True or False. If False, give the Correct statement
1.) Heat is a kind of energy that flows from A hot body to a cold body.
Answer: True
2.) Steam is formed when heat is released From water.
Answer: False because when heat is released from water it leads to the formation of ice.
3.) Thermal expansion is always a Nuisance.
Answer: False, as thermal expansion is not a nuisance but a beneficial to us.
4.) Borosilicate glass do not expand much On being heated.
Answer: True
5.) The unit of heat and temperature are The same.
Answer: False. The unit of heat is joule and Kelvin is the unit of temperature.
IV.) Give reasons for the following
1.) An ordinary glass bottle cracks when Boiling water is poured into it, but a Borosilicate glass bottle does not.
Answer: This happens because the coefficient of thermal expansion is low in borosilicate glass i.e. they do not expand on heating. Therefore they can withstand boiling water as compared to normal glass.
2.) The electric wire which sag in summer Become straight in winter.
Answer: Due to the heat present in the surrounding, the electric wire is expanded by high temperature. So, it sags in summer. On the other hand in winters, due to low temperature it contracts and become straight.
3.) Rivet is heated before fixing in hole to Join two metal plates.
Answer: Rivet gets expanded on heating and becomes soft. As to form a new head, one side of the rivet is hammered. It ultimately gets contracted upon cooling down and hold the two metal plates tightly.
V.) Match the following.
Answer:
- Heat – joule
- Temperature – kelvin
- Thermal Equilibrium – No heat flow
- Ice cube – 0°C
- Boiling water – 100°C
VI.) Analogy
- Heat : Joule :: Temperature : ________
Answer: Kelvin
- Ice cube : 0°C :: Boiling water :_____________
Answer: 100°C
- Total Kinetic Energy of molecules: Heat :: Average Kinetic Energy : __________
Answer: Temperature
VII.) Give very short answer
1.) Make a list of electrical equipments at Home which we get heat from.
Answer: At home we get heat from equipments such as water heater, convection heater, Electric kettle and microwave oven.
2.) What is temperature?
Answer: The average kinetic energy of the particles of an object can be measured with a physical quantity called temperature.
3.) What is thermal expansion?
Answer: When a substance is heated , it leads to expansion of the particles within the substance. This is called Thermal expansion.
4.) What do you understand by thermal Equilibrium?
Answer: When there is no flow of thermal energy between two physically present objects. In such a case, both the objects are unaffected by each other’s temperature. This condition is called Thermal equilibrium.
VIII.) Give short answer
1.) What difference do you think heating The solid will make in their molecules ?
Answer: Changes in molecules of an object upon heating:
- They will be an increase in the movement and vibration of molecules.
- Increase in the temperature of an object.
- There will be an increase in distance between molecules.
2.) Distinguish between heat and Temperature.
Answer:
Heat |
Temperature |
It is the total kinetic energy present in the particles of an object. |
It is the average kinetic energy of the particles of an object. |
SI unit is joule |
SI unit is Kelvin |
It depends on the quantity of molecules present in an object. |
It depends on Measuring only how hot or cold an object is. |
IX.) Answer in detail
1.) Explain thermal expansion with suitable Examples.
Answer: When a substance is heated , it leads to expansion of the particles within the substance. This is called Thermal expansion. For example:
- Rivetting – Two steel plates are joined together by using rivets. Through the hole a hot rivet is driven in the plates. As to form a new head, one side of the rivet is hammered. Contraction of rivet will take place upon cooling of the rivet , thereby holding the two metal plates tightly.
- Electric wire – Due to the heat present in the surrounding, the electric wire is expanded by high temperature. So, it sags in summer. On the other hand in winters, due to low temperature it contracts and become straight.
X.) Questions based on Higher Order Thinking Skills.
1.) When 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?
Answer: On a winter night if a window is left open, I’ll feel uncomfortable as the heat that was already present in the room will escape slowly. There will be a transfer of heat from high to low temperature. Also, the room temperature will decrease due to entering of cold air through the window.
2.) Suppose your normal body temperature Were lower than what it is. How would The sensation of hot and cold change?
Answer: Hypothermia is a condition where the body temperature is lower than normal. A cold sensation can be felt by the body in such a case. Our blood vessel narrows when we feel cold, as a result it leads to reduce in the flow of blood to our skin, thereby saving body heat.
3.) If 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.
Answer: Thermal expansion takes place when an object is heated. So the diameter of the hole of a circular disk will increase upon heating the disk.