Tag: heat and temperature

Quizzes (7) Questions (38)

Questions Related to heat and temperature

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

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?

  1. $10.3\space seconds/day$

  2. $20.6\space seconds/day$

  3. $5\space seconds/day$

  4. $20\space minutes/day$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

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

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

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

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

  4. $\dfrac{ay+bx}{x-y}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Real expansion gamma_R = gamma_apparent + gamma_vessel. Using the given ratios and two vessels, one can derive the expression for real expansion.

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

Gaps are left between railway tracks because.

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

If a bimetallic strip is heated, it will

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

Iron or steel is used in reinforcement in concrete because

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  1. Zero for that mixture

  2. Infinity for that mixture

  3. Negative for that mixture

  4. Positive for that mixture
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

Which of the following statement is wrong?

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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

  1. We should cool the system

  2. We should heat the system

  3. We should apply external force

  4. It cannot be separated
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  1. always increase

  2. always decrease

  3. remains the same

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
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.