Expansion and Contraction

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Question 10

Paheli had brought a new bottle of pickle from the market. She tried to open the metal cap to taste it but could not do so. She then took a bowl of hot water and immersed the upper end of the bottle in it for five minutes. She could easily open the bottle now. Can you give the reason for this

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Question 7

Iron rim is made slightly smaller than the wooden wheel. The rim is usually heated before fixing into the wooden wheel because on heating the iron rim
(a) expands and fits onto the wooden wheel
(b) contracts and fits onto the wooden wheel
(c) no change in the size take place
(d) expands first, then on cooling contracts and fits onto the wooden wheel

Q. An iron rod is heated. Which of the following statement about it is incorrect?

1. The rod expands.
2. The rod almost comes to the same size on cooling.
3. The change, in this case, is reserved.
4. The rod changes its shape and the change cannot be reversed.

Q.

Metal pipes are used to carry water, sometimes burst in the winter because

1. Metal contracts more than water

2. Water expands when it freezes

3. Outside of the pipe expands more than inside

4. Outside of the pipe contracts more than the inside

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7. Things that are placed in an object simply get hot on heating but the shape of that object remains unchanged. Write two examples to support this sentence.

Q. An iron rod _____ on heating.

1. evaporates
2. condenses
3. expands
4. contracts

Q. Which of the following statement about a heated iron rod is incorrect?

1. The change, in this case, is reversible.
2. The rod changes its shape and the change cannot be reversed.
3. The rod expands.
4. The rod almost comes to the same size on cooling.

Q. Chanakya on his way home saw a farmer digging the soil. He observed that digging tool had an iron blade fixed to a wooden handle. He wondered how the iron blade gets fixed to a wooden handle even when the iron ring is smaller than a wooden handle. What do you think can be the way to do this?

1. Cooling the iron ring
2. Cutting the iron ring
3. Heating the iron ring
4. Welding the iron ring

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5. When a spring is pulled, its shape and size change. From this example, what do you understand?

Q. Chanakya on his way home saw a farmer digging the soil. He observed that digging tool had an iron blade fixed to a wooden handle. He wondered how the iron blade gets fixed to a wooden handle even when the iron ring is smaller than a wooden handle. What do you think can be the way to do this?

1. Heating the iron ring
2. Cooling the iron ring
3. Cutting the iron ring
4. Welding the iron ring

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Statement B: Cooling a metal can also bring about change in its shape.

1. Both statements are correct

2. Statement A is false; Statement B is true

3. Both the statements are false

4. Statement A is true; Statement B is false

Q. In bullock carts, the iron rim is usually heated before fixing to the wooden wheels, because on heating, the iron:

1. Contracts and fits to the wooden wheel
2. Expands and fits to the wooden wheel
3. First expands and then contracts, thus fitting to the wooden wheel
4. First contracts and then expands, thus fitting to the wooden wheel

Q.

3. An iron ring is heated. Which of the following statements about it is incorrect?

1. The ring expands

2. The ring almost comes to the same size on cooling.

3. The change in this case is reversed.

4. The ring changes its shape and the change cannot be reversed.

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A struck stopper of a bottle can be removed easily by pouring hot water on it.

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Give reasons for the following statement.

One side of the iron girdles of the bridge are placed on rollers.

Q. An iron ring is heated. Which of the following statements is incorrect for the given iron ring?

1. The ring expands
2. The ring comes to the same size upon cooling
3. The change occurring, in this case, is reversible
4. The shape of the ring changes and the change is irreversible

Q. An iron ring is heated. Which of the following statements is incorrect for the given iron ring?

1. The ring expands
2. The ring comes to the same size upon cooling
3. The shape of the ring changes and the change is irreversible
4. The change occurring, in this case, is reversible

Q. Iron on heating

1. contracts
2. expands
3. contracts and then expands
4. expands and then contracts

Q.

In summers, electric wires sag a little as ___________ on heating.

1. non-metals expand

2. metals expand

3. non-metals contract

4. metals contract

Q. When subjected to stress, the property with which it breaks without significant deformation is :

1. conductivity
2. ductility
3. brittleness
4. tensile strength