**Balbharati Class 8 General Science Solutions Measurement and Effects of Heat**

Welcome to NCTB Solutions. Here with this post we are going to help 8th class students for the Solutions of Balbharati Class 8 General Science Book Chapter 14, Measurement and Effects of Heat. Here students can easily find step by step solutions of all the questions in Measurement and Effects of Heat. Also our Expert Science Teacher’s solved all the problems with easily understandable language with proper guidance so that all the students can understand easily. Here in this post students will get chapter 14 solutions. Here all the Question Answer are based on Balbharati latest syllabus. Here all the question and answer are based on Maharashtra State Board latest syllabus.

**Measurement and Effects of Heat Exercise question Solutions :**

**Question no – (1) **

**Answer : **

**(A) Whom should I pair with**

(a) Temperature of a healthy human body → (ii) 98.6° F

(b) Boiling point of water → (iv) 212°F

(c) Room temperature → (i) 296 K

(d) Freezing point of water → (iii) 0°C

**(B) True or False **

(a) The temperature of a substance is measured in Joules

= This statement is **False.**

Because, The temperature of a substance is measured in Celsius, Kelvin or Fahrenheit.

(b) Heat flows from an object at higher temperature to an object at lower temperature

= This statement is **True.**

(c)Joule is the unit of heat

= This statement is **True.**

(d)Objects contract on heating

= This statement is **False.**

Because, Objects expand on heating.

(e) Atoms of a solid are free

This statement is **False.**

Because, Atoms of a solid are fixed.

(f) The average kinetic energy of atoms in a hot object is less than the average kinetic energy of atoms in a cold object.

This statement is **False.**

Because, The average kinetic energy of atoms in a hot object is more than the average kinetic energy of atoms in a cold object.

**(C) 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 __Average__ __kinetic__ __energy__** of atoms **kinetic energy of the atoms in a substance.

(d) The heat contained in a substance is the measure of the ** Total** kinetic energy of atoms in the substance.

**Question no – (2) **

**Answer : **

Shivani’s tea will be ready much before Nisigandha because in Shivani’s case, the amount of the flame that is in contact with the vessel is very much high compared to the solar cooker due to which the flow of heat into the vessel containing water will be faster. Thus, the time taken for the tea to be prepared is less in stove than in solar cooker.

**Question no – (3) **

**Answer : **

**(a)** A clinical thermometer is used to measure body temperature between 35°C to 42°C. It has a long and narrow tube with a bulb at one end, the tube is partially filled with alcohol and vacuum. The tube has markings on it to read the temperature accordingly.

The thermometer used in laboratory has a temperature measuring range from 40°C to 110°C or even larger but has the same working principle as of a clinical thermometer.

**(b) The difference between heat and temperature are as follows**

**Heat :**

(i) Heat is a measure of total kinetic energy of the atoms.

(ii) It is measured in Joule.

**Temperature :**

(i) Temperature is the measure of average kinetic energy of atoms.

(ii) It is measured in Celsius, Kelvin and Fahrenheit.

**(c)** A calorimeter like a thermoflask has two vessels an inner and outer one. The inner vessel is made of copper and is isolated from the surroundings. A thermometer for measuring the temperature and a stirrer for stirring the liquid is fixed in it. Water at a fixed temperature is placed in the calorimeter.

**(d)** Rails has gaps at specific distances because if there were no gaps then during summer the tracks will expand and create a bulge which may lead to accidents.

**(e)** We can define a volumetric expansion coefficient for a liquid as follows V2 = V1 (1 + β ΔT). Here, ΔT is the change in temperature and V1 and V2 are the initial and final volumes of the liquid.β is the volumetric expansion coefficient of the liquid.

We can determine the expansion coefficient for a gas as follows V2 = V1 (1 + β ΔT). Here, ΔT is the change in temperature and V1 and V2 are the initial and final volumes of the gas at constant pressure. β is the constant Pressure expansion coefficient of the gas.

**Question no – (4) **

**Answer : **

**(a)** Let the temperature in Celsius be F⁰

So the temperature in Fahrenheit will be 2F⁰

We know that, (F – 32)/9 = C/5

So by using the formula we get

(2F – 32)/9 = F/5

(2F – 32)5 = 9F

10F – 160 = 9F

10F – 9F = 160

F = 160

Hence, the temperature in Fahrenheit

= 2F = 2 × 160

= 320⁰F

**(b)** length of the roads = 20 m = 2000 cm at 18⁰C

Since the distance between two rods is 0.4 cm, the distance

each rod can expand up to is 0.2 cm

Linear expansion coefficients of iron is 11.5 × 10⁶

We know the formula of linear expansion is

ΔL= λ × L1 × ( T2 – T1)

0.4 = 11.5 × 10⁶ × 20000 × (T2 – 18)

T2 – 18 = 0.4/ 20000 × 11.5 × 10⁶

T2 = 18 + 0.4/20000 × 11.5 × 10⁶

T2 = 35.4⁰C

**(c) **Initial length in cm

= 324 × 100

= 32400 cm

ΔT (Change in temperature)

= 30℃ – 15℃

= 15℃

Coefficient for linear expansion = 11.5 × 10⁶

By using the formula of linear expansion we get

Δl = λ × l1 × ΔT

= 32400 × 11.5 × 10⁶ × 15

= 5.6 cm

**(d)** Using Q = m× c × ΔT we can say that ΔT= Q/mc

Here ΔT is the change in temperature

Since ΔT is same in both the substances we can say that

Q1/m1c1 = Q2/m^{2}c^{2}

Putting the values of all the variables we get

Q/mc = 4Q/m^{2} × 2c

m^{2} = 4Qmc/2cQ

m^{2} = 4m/2

Therefore, m^{2 }= 2m

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