Tag: physics

Questions Related to physics

A man wishes to fit an aluminium ring on steel rod of 1 cm diameter and found it is 0.01 cm smaller in diameter. How much should the on temperature be raised before it just slips on the
$(\alpha _A = 25 \times 10^{-6}/^oC;$ $10 \times 10^{-6}/^oC)$

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. $40^oC$

  2. $50^oC$

  3. $25^oC$

  4. $60^oC$

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Correct Option: A
Explanation:

${l _2} = {l _1}\left( {1 + {\alpha _A}\Delta T} \right)$

${l _2} = {l _1} + {l _1}{\alpha _A}\Delta T$

$\displaystyle {{{l _2} - {l _1}} \over {{l _1}}} = {\alpha _A}\Delta T$

$\displaystyle {{0.01 \times {{10}^{ - 2}}} \over {1 \times {{10}^{ - 2}} \times 25 \times {{10}^{ - 6}}}} = \Delta T$

$\Delta T = {40^0}C$

Which of the following physical quantities is measured in calories ? 

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. Heat energy

  2. Force

  3. Momentum

  4. Temperature

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Correct Option: A
Explanation:

1 calorie: The amount of energy required to warm $1\ g$ of air-free water from $14.5^oC\ to\ 15.5^oC$ at a constant pressure of $101.325\ kPa$ $(1 atm)$

Name the S.I. unit of heat.

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. Joule

  2. Kelvin

  3. Degree centigrade

  4. All of the above

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Correct Option: A
Explanation:

Answer is (A).

It has the same unit as of energy that's Joule.

State the S.I. unit of heat capacity.

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. $ J^{-1}K^{-1}$

  2. $ JK^{-2}$

  3. $ JK$

  4. $ JK^{-1}$

Show answer
Correct Option: D
Explanation:

The S.T. unit of heat capacity is heat required per degree rise in temperature. So it is $JK^{-1}$

1 cal = _________

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. 10 joules

  2. 4.18 joules

  3. 4.18 dynes

  4. None of these

Show answer
Correct Option: B
Explanation:

1 cal = 4.18 joules

C.G.S unit of heat is calorie.
S.I. unit of heat is joule.

The SI unit of heat is:

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. calorie

  2. joule

  3. dyne

  4. newton

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Correct Option: B

Therm is a unit of

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. heat

  2. temperature

  3. thermometry

  4. mass

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Correct Option: A
Explanation:

The therm (symbol, thm) is a non-SI unit of heat energy equal to100000 British thermal units (Btu). It is approximately the energy equivalent of burning 100 cubic feet (2.83 cubic metres) – often referred to as 1 CCF – of natural gas.

For a gm molecule of an ideal gas

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. ${PV}/{T} = 2$ calories

  2. ${PV}/{T} = 4.2$ calories

  3. ${PV}/{T} = 4.31$ calories

  4. ${PV}/{T} = 4.2 \times {10}^{7}$ ergs

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Correct Option: B

The quantity of heat energy required to change the temperature of one gram of water by one degree Celsius is known as

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. 1 joule

  2. 1 kilocalorie

  3. 1 calorie

  4. 1 ampere

Show answer
Correct Option: C
Explanation:

The amount of heat required to raise the temperature of one gram of water  through $ 1 ^{o}$ (from $14.5^{o}C$ to $15.5^{o}C$), is called one calorie.

One calorie is defined as

physics measurement and effects of heat sources of heat introduction to heat measuring temperature

  1. The amount of heat energy required to raise the temperature of $1\ g$ water by $1^o\ C$

  2. The amount of heat energy required to raise the temperature of $1\ kg$ water by $1^o\ C$ 

  3. The amount of heat energy required to raise the temperature of $1\ g$ water by $1^o\ F$ 

  4. The amount of power required to raise the temperature of $1\ g$ water by $1^o\ C$ 

Show answer
Correct Option: A
Explanation:

The amount of heat energy required to raise the temperature of 1 g water by $1^o\ C$ is called one calorie.