Tag: physics

Questions Related to physics

The internal energy change when a system goes from state A to B is $40$ kJ/mole. If the system goes from A to B by a reversible path and returns to state A by an irreversible path what would be the net change in internal energy?

physics energy and its forms idea of energy introduction to work and energy work and energy

  1. $40$ kJ

  2. $> 40$ kJ

  3. $< 40$ kJ

  4. Zero

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Correct Option: D
Explanation:
For a cyclic process the net change in the internal energy is zero because the change in internal energy doesnot depend on the path.

Which of the following can be negative 

physics energy and its forms idea of energy introduction to work and energy work and energy

  1. Kinetic energy

  2. Potential energy

  3. Mechanical energy

  4. All of these

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Correct Option: B,C
Explanation:

Mechanical energy & potential energy can be negative.

$\therefore$ Option $B$ and $C$.

If the unit of force and length be each increased by four times, then the unit of energy is increased by

physics energy and its forms idea of energy introduction to work and energy work and energy

  1. 16 times

  2. 8 times

  3. 2 times

  4. 4 times

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Correct Option: A
Explanation:

Unit of Energy = Unit of Force $\times$ Unit of length 
So if we increase unit of length and force, each by four times, then unit of energy will increase by sixteen times.  

Select the correct option given below:
How much work can be obtained from 100 calories of heat energy?

physics the essence of change forms of energy and energy conservation energy for everything forms of energy

  1. 100 J

  2. 420 J

  3. 42 J

  4. 4200 J

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Correct Option: B
Explanation:

$1\ cal=4.2\ J$

$\because$ Work done = heat obtained in calories $\times 4.2$

or $W=100 \times 4.2=420 J$

Which type of energy does the food we eat have.?

physics the essence of change forms of energy and energy conservation energy for everything forms of energy

  1. Electrical energy

  2. Chemical energy.

  3. Solar energy

  4. Sound energy

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Correct Option: A
Explanation:

Chemical energy

Energy associated with moving objects is called:

physics the essence of change forms of energy and energy conservation energy for everything forms of energy

  1. Potential energy

  2. Kinetic energy

  3. No energy

  4. Work

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Correct Option: B
Explanation:

energy which a body possesses by virtue of being in motion.

The form of energy stored in kerosene is:

physics the essence of change forms of energy and energy conservation energy for everything forms of energy

  1. chemical

  2. heat energy

  3. magnetic

  4. mechanical

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Correct Option: A
Explanation:

Kerosene is the by-product of crude oil, which is a fossil fuel. In fossil fuels, energy is stored in the form of chemical energy, which is converted into heat and light energies when burnt.

Heat is a form of :

physics the essence of change forms of energy and energy conservation energy for everything forms of energy

  1. Force

  2. Energy

  3. Work

  4. Simple machine

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Correct Option: B
Explanation:

Heat is a form of energy.  Heat energy is transferred from one body to another as the result of a difference in temperature.

Its SI unit is $\textrm {Joule}$.

A solar cell converts solar energy into:

physics the essence of change forms of energy and energy conservation energy for everything forms of energy

  1. Chemical energy

  2. Light energy

  3. Electrical energy

  4. Muscular energy

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Correct Option: C
Explanation:

In a solar cell, solar energy from the Sun is converted into electrical energy. This electrical energy is used by the various electrical appliances.

Hydro-electric power generates

physics the essence of change forms of energy and energy conservation energy for everything forms of energy

  1. Electrical energy

  2. Nuclear energy

  3. Thermal energy

  4. None of these

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Correct Option: A
Explanation:

Hydro-electric power is the process where moving water rotates the turbine. Here potential energy of water converts into kinetic enery of water when waters falls downwards from a height.

After that kinetic energy of water transferred to kinetic energy of turbine and turbine starts rotating. 
After this turbine's kinetic energy is converted into electrical energy and in this way electricity is generated. 
Hence hydro-electric power generates electrical energy.