Tag: substances, objects and energy

Questions Related to substances, objects and energy

The fossil fuels include:

evs solar energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy solar power plant production of electricity from solar energy solar energy and its applications

  1. Uranium

  2. Soil

  3. Natural gas

  4. Plants

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Correct Option: C
Explanation:

Fossil fuels are formed when plants and marine species are buried below ground and are subjected to immense pressure and temperature for thousands of years. Examples include coal, petroleum and natural gas.

A body is falling freely under the action of gravity alone in vacuum. Which of the following quantities remain constant during the fall?

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. Kinetic energy

  2. Potential energy

  3. Total mechanical energy

  4. Total linear momentum

Show answer
Correct Option: C
Explanation:
As the body is falling freely under gravity, the potential energy decreases continuously and kinetic energy increases continuously as all the conservative forces are doing work. So, total mechanical energy $(PE + KE)$ of the body will be constant.
At point A total mechanical energy will be $EA = K.E + P.E$
$E _{A}=\dfrac{1}{2}mv^{2}+m _{g}H$
As velocity will be zero at $A$, so its kinetic energy will be zero 
$E _{A}=M _{g}H$
Velocity at point $B$ will be 
$V _{B}=\sqrt{2gh}$
So energy at point $B$ will be 
$E _{B}=KE+PE$
$E _{B}=\dfrac{1}{2}m(2gh)+mg(H-h)$
$E _{B}=mgh+mgH-mgh$
$E _{B}=mgH$
Now velocity at point $C$ will be 
$V _{C}=\sqrt{2gh}$
So energy at point $C$ will be
$ E _{C}=KE+PE$
$E _{C}=\dfrac{1}{2}m(2gH)+mg(0)$
So, total mechanical energy will remain same (if we neglect the air friction).

While falling

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. Potential energy

  2. Kinetic energy

  3. Both A & B

  4. None

Show answer
Correct Option: C
Explanation:

While it is falling it has certain velocity,as kinetic energy is defined as the virtue of its state of motion it will have kinetic energy.As it is at certain height it will have Potential energy which is defined by virtue of state of its position.Hence ball has both potential and kinetic energy.

A body rolling down a hill has

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. K.E. only

  2. P.E. only

  3. Neither K.E. nor P.E

  4. Both (a) and (b)

Show answer
Correct Option: D
Explanation:

While rolling down from hill a body will have some Potential energy due to height wrt to ground and due to rolling it will have some Kinetic energy .As it will keep rolling down , Its PE will change into KE

So $E _{Total}=mgh+\dfrac{mv^2}{2}$

A flying aeroplane has:

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. only potential energy

  2. only kinetic energy

  3. both potential and kinetic energy

  4. none of these

Show answer
Correct Option: C
Explanation:

An flying aeroplane required some work to be done against gravity to go upto that much height that work will be stored as potential energy of the body. Also aeroplane has some mass and moving with some velocity so has some kinetic energy also. 

So this poses both potential as well as kinetic energy.

A body rolling down a hill has:

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. K.E. only

  2. P.E. onley

  3. neither K.E. and P.E.

  4. both K.E and P.E

Show answer
Correct Option: D
Explanation:

Taking toe of the hill as refrence point so some work against the gravity is done to raise the body to top of the hill so it poses some potential energy equal to mgh where m is mass and g is acceleration due to gravity and h is vertical height.

Also he is moving so he must have some kinetic energy.
So body rolling along the hill have both kinetic as well as potential energy.

Which of the following has both kinetic energy and potential energy ?

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. A flying bird

  2. A bent bow about to shoot an arrow

  3. An athlete running at full speed

  4. None of the above

Show answer
Correct Option: A
Explanation:

Since the bird is flying is must be at some distance from the ground and Potential energy is present when there is some height associated with that object (Since P.E = mgh). Also  the bird has mass and thus gravity will be acted on it. Kinetic energy is present for an object if it has velocity.This a flying bird has both kinetic energy and potential energy.

Kinetic energy and potential energy are the two forms of

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. thermal energy

  2. nuclear energy

  3. chemical energy

  4. mechanical energy

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Correct Option: D
Explanation:

There are two different forms of mechanical energy,

i.e. kinetic energy and potential energy.

Identify an example of kinetic mechanical energy?

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. A loaded gun

  2. A set mouse trap

  3. An elevated wrecking ball

  4. A compressed spring

  5. A bike rolling down a hill

Show answer
Correct Option: E
Explanation:

A loaded gun, a set mouse trap and a compressed spring are examples of elastic potential energy.

An elevated wrecking ball is an example of gravitational potential energy.
A bike rolling down a hill is an example of kinetic energy, where potential energy is constantly converting in the kinetic energy of the bike as given by $\dfrac{1}{2}mv^2$.

Which of the following type of wave is created by solar energy?

physics types of energy renewable and non-renewable resources renewable and non-renewable sources of energy substances, objects and energy

  1. mechanical

  2. electromagnetic

  3. terminal

  4. physical

  5. nuclear

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Correct Option: B
Explanation:

Sun gives out light, which is an electromagnetic wave. Several nuclear reactions take place in Sun's core and thus light is produced.