Thermal Expansion & Contraction (ConcepTests)

Thermal Expansion & Contraction (ConcepTests)

For the next question, think through silently and select a choice for yourself.

No discussion allowed.

Find a person near to you who has a different answer from you.

Each of you will try to convince the other person to go with your own answer. At the end of 3 min, both of you should agree to go with only one of the answer.

Open Ended

together with your partner, give your reasoning for how you both came up with the answer. You have 3 mins.

Multiple Choice

When a metal ring is heated :

• the inner radius decreases abd outer radius increases

• the outer radius decreases abd inner radius increases

• both inner and outer radii increase

• both inner and outer radii decrease

Correct option is

C

• Both inner and outer radii increase

  When a metal ring is heated both inner and outer radii increase. 

• This can be understood better by visualizing that the ring in reality is a rod bent into a circle. That rod will expand upon heating. The same bar bent into a ring thus also expands. This is an expansion of the ring perimeter and thus its diameter (the hole). 

Multiple Choice

Which of the following statement is/are incorrect.

(i) 2 thin woollen sweaters are warmer than a thick woollen sweater

(ii) it saves fuel if we cook food in a vessel which is blackened at the bottom and polished from the sides

(iii) the cable wires between two poles are left loose because in summers, the wires do not break on expanding

• (i) only

• (i) and (ii)

• only (iii)

• (i) and (iii)