Tag: concept of energy

Questions Related to concept of energy

A body at rest have-

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. Energy

  2. Momentum

  3. Speed

  4. Velocity

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Correct Option: A
Explanation:

A body at rest will have thermal energy, and may even have Potential energy.

kg $m^2S^{-2}$ represents the unit of :

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. kinetic energy only

  2. work done only

  3. potential energy only

  4. all the above

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Correct Option: D
Explanation:

Work done is same as energy which is measured in joules. 1 joule is same as 1 newton expanded over 1 meter which is force multiplied by distance.

Force is defined as mass into acceleration. Hence if we accelerate 1kg mass by 1m/s$^{2}$ in a straight line for a distance of 1 meter, we have indirectly expanded 1 joule of energy .
Also acceleration is distance per second squared.
Thus we have mass $\ast$ acceleration $ast$ distance which is Kg m$^{2}$ S$^{-2}$.

A body at rest can have:

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. speed

  2. energy

  3. momentum

  4. velocity

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Correct Option: B
Explanation:

If a body is at rest then its position does not changes if position is not changing then $\frac{dx}{dt}=0$ so velocity is zero.

If Instantanious velocity is zero then speed is also zero this means if speed is zero then kinetic energy is also zero.
If v=0 then mv=0 i.e. momentum is also zero.
But a body raised upto some height against gravity and is at rest but it poses some potential energy which when released will be converted to kinetic energy.
So a body at rest can poses only potential energy from all these options.

A man carries a heavy box on his head on a horizontal plane form one place to another. In this he does

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. Maximum work

  2. No work

  3. Negative work

  4. Minimum work

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Correct Option: B

The capacity to do work is called :

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. Energy

  2. Force

  3. Motion

  4. Velocity

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Correct Option: A
Explanation:

Energy and work Energy is the capacity to do work, so option A is best possible answer. 

What is the value of 1 calorie in joules?

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. 9 joules

  2. 4.18 joules

  3. 4.16 joules

  4. 8 joules

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Correct Option: B
Explanation:

It is a fact that

$1\thinspace calorie = 4.184\thinspace J$

The CGS unit of energy is :

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. Dyne

  2. Erg

  3. Centimetre

  4. Pascal

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Correct Option: B
Explanation:

S.I. unit of energy is $N-m$ which is also known as $joule$ and 


CGS unit of energy is $Dyne-cm$ which is also known as $erg$.

and $1 erg = 10^{-7} J$

So answer to the question is B.

$1eV=$

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. $16\times{10}^{-19}J$

  2. $1.6\times{10}^{-19}J$

  3. $1.6\times{10}^{19}J$

  4. $1.6\times{10}^{-19}erg$

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Correct Option: B
Explanation:

$1eV$ is the energy gained by an electron when it is accelerated through a potential difference of $1volt$.
So, $1eV=$ charge of an electron $\times$ $1volt$ $=1.6\times{10}^{-19}coulomb$ ${\times}1volt=1.6\times{10}^{-19}J$

Which physical quantity is measured in $calorie$?

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. Heat energy

  2. Displacement

  3. Force

  4. Intensity of sound

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Correct Option: A
Explanation:

Heat energy is usually measured in $calorie$.

$1J=$

physics energy : forms and sources concept of energy energy for everything forms of energy

  1. $4.18calorie$

  2. $2.4calorie$

  3. $0.24calorie$

  4. $100calorie$

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Correct Option: C
Explanation:

Heat energy is usually measured in $calorie$. $1calorie$ is the heat energy required in raising the temperature of $1g$ of water from ${14.5}^{0}C$ to ${15.5}^{0}C$. It is related to $J$ as $1J=0.24calorie$.