Tag: physics

Questions Related to physics

The vast amount of sea weeds present in oceans may provide an endless source of

physics sources of energy wave energy tidal energy wave power and tidal power

  1. nuclear energy

  2. methane

  3. thermal energy ocen

  4. none of these

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Correct Option: B

The energy available due to the difference in the temperature of water at the surface of the ocean and at deeper levels is called

physics sources of energy wave energy tidal energy wave power and tidal power

  1. tidal energy

  2. wind energy

  3. solar energy

  4. none of these

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Correct Option: D

What are the energy from sea in the below options?

physics sources of energy wave energy tidal energy wave power and tidal power

  1. Tidal energy

  2. Wave energy

  3. Ocean thermal energy

  4. All of above

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Correct Option: D
Explanation:

Tidal -Because of  gravitation pull of Moon, tides in sea are seen.Tidal energy is a form of hydropower which utilizes energy from tides to produce electricity.
Wave - Waves are good source of energy. Waves from the sea are used to run the turbines to generate electricity.
Ocean thermal energy - Water at sea surface is hot during daytime and at lower level is cold. This temperature difference is used to produce energy (electric).

Wave energy harnesses :

physics sources of energy wave energy tidal energy wave power and tidal power

  1. winds produced by huge waves.

  2. waves formed by tides.

  3. potential energy of normal waves.

  4. kinetic energy possessed by huge waves.

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Correct Option: D
Explanation:

In wave energy, kinetic energy possessed by huge waves is trapped to generate electricity with the help of a machine called wave energy convertor. 

Tidal energy is harnessed by:

physics sources of energy wave energy tidal energy wave power and tidal power

  1. transporting sea water to a close dam.

  2. constructing a submerged dam.

  3. constructing a dam across a narrow opening to the sea.

  4. constructing an overhead dam.

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Correct Option: C
Explanation:

Difference in sea-levels due to tides during different times of day gives us tidal energy. Tidal energy is harnessed by constructing a dam across a narrow opening to the sea. A turbine fixed at the opening of the dam converts tidal energy to electricity.

Electricity production from wave energy requires:

physics sources of energy wave energy tidal energy wave power and tidal power

  1. strong waves

  2. mild waves

  3. Either (A) or (B)

  4. None of the above

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Correct Option: A
Explanation:

Wave energy would be a viable proposition only where waves are very strong.

Which of the following systems of units is not based on units of mass, length and time alone ?

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. SI

  2. MKS

  3. CGS

  4. FPS

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Correct Option: A
Explanation:

SI system is based on seven fundamental units. These fundamental units are Kelvin, Second, Kilogram, Metre, Candela, Mole and Ampere.

$1 N = Z  kgf$ (approx.), then what is the value of $Z$?

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. 0.1

  2. 1

  3. 10

  4. 0

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Correct Option: A
Explanation:

The kilogram-force (kgf or kgF) is a gravitational metric unit of force. It is equal to the magnitude of the force exerted by one kilogram of mass in a $10\ ms^{-2}$ gravitational field (standard gravity, a conventional value approximating the average magnitude of gravity on Earth).Therefore one kilogram-force is by definition equal to 10 N

So 1 kgf=10N
hence 1N=0.1 kgf  , Z=0.1

What is the C.G.S. unit of force? 

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. N

  2. N.m

  3. dyne

  4. dyne.cm

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Correct Option: C
Explanation:

CGS unit of Force = $dyne$
The dyne is a unit of force specified in the centimetre-gram-second (CGS) system of units, a predecessor of the modern SI. One dyne is equal to $10^{-5}$ N.

What is the ratio of CGS to MKS unit of acceleration?

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. $\dfrac{m}{cm}$

  2. $\dfrac{m}{s}$

  3. $\dfrac{cm}{s}$

  4. $\dfrac{cm}{m}$

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Correct Option: D
Explanation:

CGS unit of acceleration $= cm/s^{2}$
MKS unit of acceleration $=m/s^{2}$
So, ratio of CGS and MKS is $\dfrac{cm}{m}$