Question

Give reasons for the following:
(a) Iron rims are heated red hot before fixing them on cart wheels.
(C) A new quilt is warmer than an old one.
(d) A brass tumbler feels much cooler than a wooden tray on a chilly day.
(e) The bottoms of cooking utensils are often kept black.
(b) A clinical thermometer has a slight bend, or kink, in its capillary tube.​

Answer 1

Answer:

$\bold \blue{Iron \: rims \: are \: heated \: red \: hot \: before \: fixing \: them \: on \: cart \: wheels.}$

a.) The iron ring to be put on the rim of a cart wheel is always of slightly smaller diameter than that of the wheel. When the iron ring is heated to become red hot, it expands and slips on to the wheel easily. When it is cooled, it contracts and grips the wheel firmly.

$\bold \pink{(C) A \: new \: quilt \: is \: warmer \: than \: an \: old \: one.}$

c.)A new quilt is warmer than an old quilt. ... When the quilt gets old, the layers of batting press against each other reducing the air spaces between them. Because of this, much air is not trapped and we do not feel warm as before.

$\bold \red{A \: brass \: tumbler \: feels \: much \: cooler \: than \: a \: wooden \: tray \: on \: a \: chilly \: day.}$

The thermal conductivity of brass is high i.e., brass is a good conductor of heat. So, when a brass tumbler is touched, heat quickly flows from human body to tumbler. Consequently, the tumbler appears colder, on the other hand wood is a bad conductor.

$\bold \purple{The \: bottoms \: of \: cooking \: utensils \: are \: often \: kept \: black.}$

Cooking Utensils are painted black from bottom to absorb more heat and get heated quickly. Cooking Utensils are highly polished from inside to reduce loss of heat and keep warm for a longer time.

$\bold \green{A \: clinical \: thermometer \: has \: a \: slight \: bend, \: or \: kink \: , in \: its \: capillary \: tube.}$

A clinical thermometer has a narrow kink in the capillary tube because when Mercury expands, it pushes through the kink, but when it's taken out of patient mouth, Mercury does not go back to the bulb beacuse if it. Hence, doctor can read the patients temperature easily .

Answer 2

Answer:

Hey bro this is your answer

This is not my answer because I am study in class 6

This is my sister's answer of class 7 and she also study in dav school So , It is a correct answer and easy Her teacher Ravi sir Tell her this answer

Explanation:

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