Tag: heat energy transfers

Questions Related to heat energy transfers

Form of energy which causes in us sensation of hotness or coldness :

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. Surface energy

  2. Heat energy

  3. Kinetic energy

  4. Potential energy

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Correct Option: B
Explanation:

It is a form of energy which causes in us the sensation of hotness or coldness for ex. If we dip our finger in hot water we have sensation of hotness.

Heat is a from of ______

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. Energy

  2. Work

  3. Power

  4. None of these

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Correct Option: A
Explanation:

In thermodynamics, heat is a type of energy transfer in which energy flows from a warmer substance or object to a colder one. It can be defined as the total amount of transferred energy excluding any macroscopic work that was done and any transfer of part of the object itself Transfer of energy as heat can occur through direct contact, through a barrier that is impermeable to matter (as in conduction), by radiation between separated bodies, by way of an intermediate fluid (as in convective circulation), or by a combination of these By contrast to work, heat involves the stochastic (random) motion of particles (such as atoms or molecules) that is equally distributed among all degrees of freedom, while work is confined to one or more specific degrees of freedom such as those of the center of mass.

When heat energy is given out by a hot substance then the kinetic energy of its molecules _________. Fill in the blank. 

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. Increases

  2. Decreases

  3. Remain same

  4. None

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Correct Option: B
Explanation:

When heat energy is given out by a hot substance, the internal energy of the substance decreases hence kinetic energy of its molecules i.e. they become slower in motion.

Greater the heat energy, ________ the body. Fill in the blank.     

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. Hotter

  2. Colder

  3. Neutral

  4. None

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Correct Option: A
Explanation:

Greater heat energy of a body means molecules of the body are moving faster i.e. they have greater kinetic energy, which gives the higher temperature to the body i.e. body is hotter.

Which of the following is false for heat?

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. It is a form of energy.

  2. It cannot be seen but only can be felt.

  3. If a body's temperature is increased, it gains heat energy.

  4. It is always produced from chemical energy.

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Correct Option: D
Explanation:

Heat is a form of energy. It can only be felt and not seen. 

Heat transferred to a body is given by
$Q=ms\Delta T$
Hence, when temperature of body is increased, it gains heat energy. It flows from hotter body to colder body. Other forms of energy can also convert to heat energy. For example, for a sliding block on a rough surface, most of the kinetic energy is converted into heat energy.

At the molecular level what can be said about Heat energy?

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. Heat energy is equal to total mechanical energy of all its molecules

  2. Heat energy is equal to total potential energy of all its molecules

  3. Heat energy is equal to total kinetic energy of all its molecules

  4. Heat energy is equal to total heat energy of all its molecules

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Correct Option: A
Explanation:

At molecular level, heat energy is equal to mechanical energy of all molecules. Mechanical energy of the molecules is the sum of total Kinetic energy and potential energy of molecules.

Select the option which describes the best definition of heat in the context of thermal energy?

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. energy possessed by a system due to movement of particles within the system

  2. the measure of thermal energy

  3. thermal energy transferred from one object to another

  4. energy possessed by an object due to the temperature of the object

  5. potential energy

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Correct Option: C
Explanation:

Heat is a thermal energy that is transferred from hotter body to a cooler body.

The mode of exchange of energy due to temperature difference is known as:

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. heat energy

  2. electric energy

  3. potential energy

  4. kinetic energy

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Correct Option: A
Explanation:

Heat energy is termed as total energy contained within a substance.

The temperature inside a refrigerator is $t _2$ $^0C$ and the room temperature is $t _1$ $^0C$. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be   

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. $\frac{t _1}{t _1 - t _2}$

  2. $\frac{t _1 + 273}{t _1 - t _2}$

  3. $\frac{t _2 + 273}{t _1 + t _2}$

  4. $\frac{t _1 + t _2}{t _1 + 273}$

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Correct Option: B

How much heat energy is gained when 5kg of water at $20^{ _-^0}C$ I brought to its boiling point? (Specific heat of water = 4.2 kJ $kg^{-1} C^{-1}$) -

physics heat energy transfers heat energy heat, internal energy and work internal energy

  1. 1680 kJ

  2. 1700 kJ

  3. 1720 kJ

  4. 1740 kJ

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Correct Option: A