Tag: different forms of energy

Questions Related to different forms of energy

When $1\ gm$. of water at $100^{\circ}C$ is converted into steam occupies $1671\ c.c.$ The amount of work done in converting water into steam is

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. $167\ J$

  2. $180\ J$

  3. $184\ J$

  4. $2098\ J$

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Correct Option: D

$1$ calorie is the heat required to increase the temperature of $1g$ of water by $1 ^ { \circ } \mathrm { C }$ from:

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. $13.5 ^ { \circ } \mathrm { C } \text { to } 14.5 ^ { \circ } \mathrm { C } \text { at } 76 \mathrm { mm } \text { of } \mathrm { Hg }$

  2. $14.5 ^ { \circ } \mathrm { C } \text { to } 15.5 ^ { \circ } \mathrm { C } \text { at } 760 \mathrm { mm } \text { of } \mathrm { Hg }$

  3. $13.5 ^ { \circ } \mathrm { C } \text { to } 15.5 ^ { \circ } \mathrm { Cat } 76 \mathrm { mm } \text { of } \mathrm { Hg }$

  4. $15.5 ^ { \circ } \mathrm { C } \text { to } 16.5 ^ { \circ } \mathrm { C } \text { at } 700 \mathrm { mm } \text { of } \mathrm { Hg }$

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Correct Option: A

If the amount of heat given to a system is $35\, J$ and the amount of work done on the system is $15\, J$, then the change in internal energy of the system is

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. $- 50\, J$

  2. $20\, J$

  3. $30\, J$

  4. $50\, J$

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Correct Option: D
Explanation:

Given,

$\Delta Q=+35J$
$\Delta W=-15J$
$\Delta U=?$
From law of thermodynamic,
$\Delta Q=\Delta U+\Delta W$
$\Delta U=\Delta Q-\Delta W$
$\Delta U=35-(-15)$
$\Delta U=35+15$
$\Delta U=50J$
The correct option is D. 

A geyser heats water flowing at the rate of 3.0 liters per minute from ${ 27 }^{ \circ  }C$ to ${ 77 }^{ \circ  }C$. If the geyser operates on a gas burner, the rate of consumption of the fuel if its heat of combustion is $4.0\times { 10 }^{ 4 }J/g$ per minute is

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. $15.75g$

  2. $4 g$

  3. $0.3 g$

  4. $0.16 g$

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Correct Option: A

A certain quantity of heat energy is given to a diatomic ideal gas which expands at constant pressure. The fraction of the heat energy that is converted into work is 

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. $\dfrac 2 5$

  2. $\dfrac 2 7$

  3. $\dfrac 1 5$

  4. $\dfrac 5 7$

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Correct Option: D
Explanation:

Supplied heat at constant pressure, 

$\Delta Q=nC _P \Delta T$
Change in internal energy,
$\Delta U=nC _V \Delta T$
ratio, $\dfrac{\Delta U}{\Delta Q}=\dfrac{nC _V \Delta T}{nC _P \Delta T}=\dfrac{C _V}{C _P}$. . . . . . . . .(1)
For diatomic ideal gas,
$C _P=\dfrac{7R}{2}\,  ,  C _V=\dfrac{5R}{2}$
From equation (1), we get
$\dfrac{\Delta U}{\Delta Q}=\dfrac{5R/2}{7R/2}=\dfrac{5}{7}$
$(5/7)^{th}$ part of heat supplied is used to increase internal energy.

A hammer of mass 1$\mathrm { kg }$ having speed of 50$\mathrm { m } / \mathrm { s }$ , hit a iron nail of mass 200$\mathrm { gm }$ . If specific heat of iron is 0.105 cal/gm'C and half the energy is converted into heat, the raise in temperature of nail is

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. $7.1 ^ { \circ } C$

  2. $9.2 ^ { \circ } \mathrm { C }$

  3. $10.5 ^ { \circ } C$

  4. $12.1 ^ { \circ } \mathrm { C }$

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Correct Option: A

In case of explosion of a bomb which of the following does not change?

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. Chemical energy

  2. Total energy

  3. Kinetic energy

  4. Mechanical energy

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Correct Option: B
Explanation:

The chemical energy possessed by the bomb after explosion converts into heat energy, sound energy, light energy i.e. into different forms of energy but remains conserved. Hence, total energy of bomb does not change, but kinetic and mechanical energy changes.

In the foregoing question, the amount of energy given to the system from A to B is:

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. 50J

  2. 60J

  3. 30J

  4. 10J

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Correct Option: A

The specific heat capacity of a metal at low temperautre (T) is given as $C _ { p } \left( k \sqrt { k } - 1 k g ^ { - 1 } \right) = 32 \left( \frac { T } { 400 } \right) ^ { 3 }$ A 100 gram vessel of this metal is to be cooled from $20 ^ { \circ } K$ to $4 ^ { \circ } \mathrm { K }$ by a special refrigerator operating at room temperature $\left( 27 ^ { \circ } \mathrm { C } \right) .$ The amount of work required to cool the vessel is:-

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. equal to 0.002$\mathrm { kJ }$

  2. greater than 0.148$\mathrm { kJ }$

  3. between 0.148$\mathrm { kJ }$ and 0.028$\mathrm { kJ }$

  4. less than 0.028$\mathrm { kJ }$

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Correct Option: A

An ideal gas heat engine operates in a Carnot's cycle between $227^{\circ}C$ and $127^{\circ}C$. It absorbs $6\times 10^{4} J$ at high temperature. The amount of heat converted into work is _____.

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. $4.8\times 10^{4}J$

  2. $3.5\times 10^{4}J$

  3. $1.6\times 10^{4}J$

  4. $1.2\times 10^{4}J$

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Correct Option: D