Tag: anomalous expansion of water

Questions Related to anomalous expansion of water

A clock which keeps correct time at $20^{\small\circ}C$, is subjected to $40^{\small\circ}C$. If coefficient of linear expansion of the pendulum is $12\times10^{-6}$ per $^{\small\circ}C$. How much will it gain or loose in time?

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. $10.3\space seconds/day$

  2. $20.6\space seconds/day$

  3. $5\space seconds/day$

  4. $20\space minutes/day$

Show answer
Correct Option: A
Explanation:

$\quad T = 2\pi\sqrt{\displaystyle\frac{l}{g}}$
$\quad \displaystyle\frac{\triangle T}{T} = 2\pi\times\displaystyle\frac{1}{2}(l/g)^{-1/2}\times\triangle l/l$
$\quad (\because T + \triangle T = 2\pi\sqrt{\displaystyle\frac{l+\triangle l}{g}})$
$\quad \therefore \displaystyle\frac{\triangle T}{T} = \displaystyle\frac{1}{2}\displaystyle\frac{\triangle l}{l} = \displaystyle\frac{1}{2}\propto\triangle\theta$
$\quad = \displaystyle\frac{1}{2}\times12\times10^{-6}\times(40-20) = 12\times10^{-5}$
$\quad \triangle T = T\times12\times10^{-5} = 24\times60\times60\times10^{-5} = 10.3\space s/day$

Coefficient of apparent expansions of a liquid in two different vessels a and b. then the real coefficient of expansions of liquid, if the ratil of volume expansion of vessels is x : y

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. $\dfrac{ay-bx}{x+y}$

  2. $\dfrac{ay+bx}{x+y}$

  3. $\dfrac{ay-bx}{x-y}$

  4. $\dfrac{ay+bx}{x-y}$

Show answer
Correct Option: A

Gaps are left between railway tracks because.

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. gaps provide the space for the tracks to expand in summer heat

  2. gaps hold the tracks firmly

  3. to produce gentle rhythmic sound when the train moves on the track

  4. it is customary to leave the gaps

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Correct Option: A
Explanation:

Railway tracks being made out of metal ( Iron ) expand due to increase in temperature in summers.

If a bimetallic strip is heated, it will

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. Bend towards the metal with lower thermal expansion coefficient.

  2. Bend towards the metal with higher thermal expansion coefficient.

  3. Twist itself into helix.

  4. Have no bending.

Show answer
Correct Option: A
Explanation:

Answer is A

A bimetallic strip consists of two metal strips fastened together. Metals are chosen that expand at different rates when the strips get hot. When one strip gets longer than the other, the combination has to bend. These strips are often used in thermostats in houses to control the house temperature. When the strip is cold, it bends one way, and as it gets hotter it bends the other way.

Iron or steel is used in reinforcement in concrete because

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. Concrete has high coefficient of expansion than iron or steel

  2. Concrete has low coefficient of expansion than iron or steel

  3. Both have nearly equal coefficient of expansions

  4. Iron or steel is a good conductor of heat

Show answer
Correct Option: C
Explanation:

The properties of thermal expansion for both steel and concrete are approximately the same as both have nearly equal coefficient of expansion . This along with excellent bendability property makes steel the best material as reinforcement in concrete structures.

Crucibles are made of mixture of quartz and silica since the linear coefficient of expansion is

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. Zero for that mixture

  2. Infinity for that mixture

  3. Negative for that mixture

  4. Positive for that mixture

Show answer
Correct Option: A
Explanation:

Its thermal expansion is practically zero. Bricks of this type are used in the melter crown of the glass furnace as they provide good resistance to creep and good mechanical strength at the operating temperature.

Which of the following statement is wrong?

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. Bimetal is used in metal thermometer

  2. Bimetals are used to generate electricity

  3. Bimetals relays are used to open or close electric circuits

  4. Bimetals is used in thermostats for regulating heating or cooling of rooms

Show answer
Correct Option: B
Explanation:

Bimetals are made of two different metals having different coefficient of expansion.  

A bimetallic strip is used to convert a temperature change into mechanical displacement.
Bimetal has the property of bending when heated,so used for open or close circuits.
Thermostats can be constructed in many ways and may use a variety of sensors to measure the temperature, commonly a thermistor or bimetallic strip. The output of the sensor then controls the heating or cooling apparatus.
Thus statement B is wrong.

The brass disc fits tightly in a hole in a steel plate. To loose the disc from hole

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. We should cool the system

  2. We should heat the system

  3. We should apply external force

  4. It cannot be separated

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Correct Option: A
Explanation:

The linear expansion of coefficient of brass is more than steel .The system must be cooled which causes more contraction in brass disc and less contraction in the hole of steel plate. The disc becomes loose.

Why the error creeps into the time shown by the pendulum clock made of ordinary metal during winter and summer.

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. In summer days are long and in winter it is small

  2. In summer, the length of the pendulum decreases, and in winter, it increases.

  3. In summer, the length of the pendulum increases, and in winter, it decreases.

  4. In summer days are small and in winters it is long

Show answer
Correct Option: C
Explanation:

The time taken for the pendulum to complete one oscillation is called period $(T)$. $T$ increases with increase in length. We know that substances expand on heating and contract on cooling.

Select the correct option given below:
There is a hole in the middle of a copper plate . When heating the plate,diameter of hole would be

physics heat and temperature anomalous expansion of water thermal expansion in solids, liquids and gases thermal expansion

  1. always increase

  2. always decrease

  3. remains the same

  4. none of these

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Correct Option: A
Explanation:

A metal expand on heating. If a hole is made in the metal plate, the hole will also expand due to the expansion of the material. It can be explained by considering the air in the region of hole and that air will also expand on heating. Therefore, diameter of the hole increases always.