Question

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Answer 1

Answer:

Ques30 . Heat describes the transfer of thermal energy between molecules within a system and is measured in Joules. Heat measures how energy moves or flows. ... Temperature describes the average kinetic energy of molecules within a material or system and is measured in Celsius (°C), Kelvin(K), Fahrenheit (°F)

Ques31(a):Sericulture, the production of raw silk by means of raising caterpillars (larvae), particularly those of the domesticated silkworm

(b)Cocoon, a case produced in the larval stage of certain animals. e.g., butterflies

(c)The pile of cocoons is placed in hot water. Hot water makes the silk fibres of cocoons to separate out. The long silk fibres are obtained by unwinding the threads from cocoons. The process of taking out silk fibres from the cocoons for use as silk is called reeling.

Ques 32:An acid is any chemical compound once dissolved in water produces a solution with hydrogen ion activity more than purified water.

A base is an aqueous substance that absorbs hydrogen ions.

Ques 33:Rainwater harvesting

Use of sprinklers in fields

Ques34:Rest and motion are the relative terms because they depend on the observer's frame of reference. So if two different observers are not at rest with respect to each other, then they too get different results when they observe the motion or rest of a body

E.g.You are standing on a platform and see a train speeding past you. the train is definitely in motion with respect to you. now, think of a passenger in the same train..to the passenger the train in at rest but he sees the platform speeding past him, meaning you appear to be in motion with respect to him

Ques35:Lightning conductor is a metal rod placed on a building and connected with the ground below to protect the building from being damaged by lightning. Its purpose is to offer a low resistance path to lightening and allow it to pass to the ground without impacting the building.

Ques36:Camouflage refers to the use of a combination of materials, illumination or colouration that makes an animal blend in with its environment, or makes it harder to spot.

E.g.An example of camouflage is a chameleon's skin, which changes colors depending on his environment.

Ques37:The houses in rural areas are built with bricks and mud so as to keep the houses warm in winters and cool in summers.

Explanation:

Tell me in the comments if anything is wrong in the answer

Answer 2

Answer:

$\orange{ \mathbb{ \large{ \huge{Hello}}}}$

${\huge{\sf{\blue{\underline {\underline{Question}}}}}}$

Find the area of a triangle, two sides of which are 18cm and 10cm and the perimeter is 42 cm :

Answer :-

Given that,

Two sides of triangle are 18 cm and 10 cm.

Perimeter of triangle is 42 cm

Let, third side of triangle be x .

So,

⟶ Perimeter = 18 + 10 + x

⟶ 42 = 28 + x

⟶ 42 - 28 = x

⟶ x = 14

Third side of triangle is 14 cm.

Now,

s = 42/2

s = 21

Semi-perimeter is 21 cm.

Area of traingle :

⟶ √21 × (21 -18)(21 -14)(21 - 10)

⟶ √21 × 3 × 7 × 11

⟶ √3 × 7 × 3 × 7 × 11

⟶ 3 × 7 √11

⟶ 21 × √11

Put √11 = 3.316

⟶ 21 ×3.316

$\longrightarrow \blue{\boxed{\bold{69.639}}\bigstar}$

★

Area of triangle is 69.636 cm²

_____________________________________

Formulas used:-

• Perimeter of triangle = Sum of all sides

• Heron's formula that is

Area of traingle = √s(s - a)(s - b)(s - c)

where,

s is semi-perimeter of triangle.

a, b and c are sides of triangle.

• Semi-perimeter = Perimeter of triangle/2