Tag: measurement and effects of heat

Questions Related to measurement and effects of heat

500 g of hot water at $60^oC$ is kept in the open till its temperature falls to $40^oC$. Calculate the heat energy lost to the surroundings by the water. (Specific heat of water $=4200 J kg^{-1} {\;}^oC^{-1})$

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. 2400 J

  2. 5000 J

  3. 40000 J

  4. 42000 J

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Correct Option: D
Explanation:

$m=500, g=0.5 kg$
$\Delta T=60-40=20^oC$
$C=4200 J kg^{-1} {\;}^oC^{-1} Q=?$
Using the formula, $Q=m C \Delta T$
$=0.5\times 4200\times 20=42000 J$
$\therefore \text {Heat lost}=42,000 J$

How much amount of heat is required to raise the temperature of 100 g of water from $30 ^oC$ to $100 ^oC$? The specific heat of water $=4.2 J g^{-1} {\;}^oC^{-1}$.

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. 25.5 kJ

  2. 29.4 kJ

  3. 30 kJ

  4. 40 kJ

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Correct Option: B
Explanation:

Mass of water, $m=100 g$
Rise in temperature $(\Delta T)$
$=(100^oC-30^oC)=70 ^oC$
Specific heat of water
$C=4.2 J g^{-1} {\;}^oC^{-1}$
Then $Q=m . C. \Delta T$
$=100 g\times 4.2 J g^{-1} {\;}^oC^{-1}\times 70 ^oC$
$=29400 J=29.4 kJ$

What quantity of heat would be given out by 200 gm of copper in cooling from $80^oC$ to $20^oC$ (Specific heat of copper $=0.09 cal g^{-1} {\;}^oC^{-1})$?

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. 1080 cal

  2. 1000 cal

  3. 1500 cal

  4. 1100 cal

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Correct Option: A
Explanation:

$m=200 g, C _{copper}=0.09 cal g^{-1} {\;}^oC^{-1}$
$\Delta T=T _1-T _2=80-20=60^oC$
$\therefore Q=mC \Delta T=200\times 0.09\times 60$
$=1080 cal$.

If $20 \ g$ of ice at $0^\circ C$ is mixed with $10 \ g$ of water at $40^\circ C$, the final mass of water in the mixture is:

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. 10 g

  2. 25 g

  3. 18 g

  4. 20 g

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Correct Option: A

A liquid P if specific heat capacity $2400 J kg^{-1} K^{-1}$ and at $70^oC$ is mixed with another liquid R of specific heat capacity $1000 J kg^{-1} K^{-1}$ at $30^oC$. After mixing, the final temperature of the mixture is $40^oC$. Find the ratio of the mass of the liquids mixed?

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. 4 : 5

  2. 8 : 5

  3. 40 : 5

  4. 48 : 5

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Correct Option: D
Explanation:

Let mass of the liquids P and R be $m _P$ and $m _R$ respectively.
According to calorimeter,
Heat lost by liquid P $=$ Heat gained by liquid R.
$\therefore m _PC _P(70-40)=m _RC _R(40-30)$
$m _P(2400)(40)=m _R(1000)(10)$
$\frac {m _P}{m _R}=\frac {2400\times 40}{1000\times 10}=\frac {48}{5}$
$\frac {m _P}{m _R}=48 : 5$

Calculate the amount of heat required to convert 5 kg of ice to $0^oC$ to vapour at $100^oC$.

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. $1.5\times 10^7 J$

  2. $2.5\times 10^7 J$

  3. $3.5\times 10^7 J$

  4. $4.5\times 10^7 J$

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Correct Option: A
Explanation:

$m=5 kg, L _f=3.36\times 10^5 J kg^{-1}$
$L _V=2.25\times 10^6 J kg^{-1}$
$C=4200 J kg^{-1} {\;}^oC^{-1}$ Then $Q=?$
$Q=$ Heat required to convert ice at $^oC$ to water $0^oC +$ Heat required to convert water at $100^oC$ to vapour at $100^oC$
$=mL _f+ms(100-0)+mL$
$=5\times 3.36\times 10^5+5\times 4200\times (100-0)+5\times 2.25\times 10^6$
$=16.8\times 10^5+21\times 10^5+112.5\times 10^5$
$=1.5\times 10^7J$

Utensils used for efficient cooking should have

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. Large heat capacity

  2. Small heat capacity

  3. Medium heat capacity

  4. Any heat capacity

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Correct Option: A

A copper calorimeter of a mass $300\ g$ contains $500\ g$ of water at a temperature of $20^\circ C$. A $500\ g$ of copper block at $100^\circ C$ is dropped into the calorimeter. If the resultant temperature is $25^\circ C$, then fond the specific heat of copper in $JKg^{-1} K^{-1}$.

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. $190$

  2. $290$

  3. $390$

  4. $490$

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Correct Option: C

Calories is defined as the amount of heat required to rise temperature of $1\ g$ of water by $1^{o}C$ and it is defined under which of the following conditions.

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. From $14.5^{o}C$ to $15.5^{o}C$ at $760\ mm$ of $Hg$

  2. From $98.5^{o}C$ to $99.5^{o}C$ at $760\ mm$ of $Hg$

  3. From $13.5^{o}C$ to $14.5^{o}C$ at $76\ mm$ of $Hg$

  4. From $3.5^{o}C$ to $4.5^{o}C$ at $76\ mm$ of $Hg$

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Correct Option: A

 Which of the following material is used to make calorimeter?

physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

  1. Glass

  2. Ebonite

  3. Metal

  4. Superconductor

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Correct Option: C