Tag: measurement and effects of heat

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Questions Related to measurement and effects of heat

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

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 $=4200 J kg^{-1} {\;}^oC^{-1})$

  1. 2400 J

  2. 5000 J

  3. 40000 J

  4. 42000 J
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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

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

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 $=4.2 J g^{-1} {\;}^oC^{-1}$.

  1. 25.5 kJ

  2. 29.4 kJ

  3. 30 kJ

  4. 40 kJ
Reveal answer Fill a bubble to check yourself
B Correct answer
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 $Q=m . C. \Delta T$
$=100 g\times 4.2 J g^{-1} {\;}^oC^{-1}\times 70 ^oC$
$=29400 J=29.4 kJ$

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

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 $=0.09 cal g^{-1} {\;}^oC^{-1})$?

  1. 1080 cal

  2. 1000 cal

  3. 1500 cal

  4. 1100 cal
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

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?

  1. <span>4 : 5</span>

  2. <span>8 : 5</span>

  3. <span>40 : 5</span>

  4. <span>48 : 5</span>
Reveal answer Fill a bubble to check yourself
D Correct answer
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.
$\therefore m _PC _P(70-40)=m _RC _R(40-30)$
$m _P(2400)(40)=m _R(1000)(10)$
$\frac {m _P}{m _R}=\frac {2400\times 40}{1000\times 10}=\frac {48}{5}$
$\frac {m _P}{m _R}=48 : 5$

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

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

  1. $1.5\times 10^7 J$

  2. $2.5\times 10^7 J$

  3. $3.5\times 10^7 J$

  4. $4.5\times 10^7 J$
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $100^oC$
$=mL _f+ms(100-0)+mL$
$=5\times 3.36\times 10^5+5\times 4200\times (100-0)+5\times 2.25\times 10^6$
$=16.8\times 10^5+21\times 10^5+112.5\times 10^5$
$=1.5\times 10^7J$

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

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

  1. $190$

  2. $290$

  3. $390$

  4. $490$
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice physics measurement and effects of heat heat exchange calorimeter measuring thermal quantities by the method of mixtures

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.

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

The calorie is defined as the amount of heat required to raise the temperature of 1g of water from 14.5C to 15.5C at standard atmospheric pressure (760 mm Hg).