Tag: the essence of change

Questions Related to the essence of change

The glow worm produces light energy from

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. Potential energy

  2. Nuclear fusion

  3. Electrical energy

  4. Chemical energy

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Correct Option: D
Explanation:

Some organisms like the glow worm have chemicals in them, which produce light.

A fast moving motorbike mainly converts _______ energy to kinetic energy.

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. chemical

  2. mechanical

  3. nuclear

  4. electrical

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Correct Option: A
Explanation:

The chemical energy of the fuel is converted to kinetic energy using the engine of the bike.

A tube light converts electrical energy into heat energy

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. True

  2. False

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Correct Option: B
Explanation:

A tubelight converts electrical energy into light energy.

An electric heater is used by us to convert electrical energy to:

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. heat energy

  2. light energy

  3. both a and b

  4. chemical energy

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Correct Option: A
Explanation:

An electric heater is used to obtain heat energy. For light energy a bulb or other light sources are used.
An electric heater is used to convert electrical energy to heat energy.

A plant usually stores its carbohydrates in its fruits. This process also shows the conversion of  _______ energy to _______ energy.

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. kinetic to potential

  2. mechanical to chemical

  3. solar to chemical

  4. none of these

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Correct Option: C
Explanation:

Plant takes heat from the sun in form of solar energy and using photosynthesis process, this energy is converted to carbohydrates.

A Wind-mill converts mechanical energy to ________ energy

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. chemical

  2. electrical

  3. solar

  4. potential

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Correct Option: B
Explanation:

Wind power is generated by the force wind exerts on the blades of a turbine, causing the turbine's shaft to rotate at a speed of 10 to 20 revolutions per minute (rpm). The rotor shaft is connected to a generator that converts mechanical energy into electrical energy.

A cyclist free-wheels from the top of a hill, gathers speed going down the hill, apply his brakes and eventually came to rest at the bottom of the hill. Which one of the following energy changes take place?

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. Potential to kinetic to heat energy

  2. Kinetic to potential to heat energy

  3. Chemical to heat to potential energy

  4. Kinetic to heat to chemical energy

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Correct Option: A
Explanation:

Considering ground as zero potential
Initially $E = U + K = U + 0 = U$
Finally $E = U + K = 0 + 0 = 0$
So, initially it had some potential energy, it was converted to kinetic energy by gaining speed, it finally became zero so energy must have been lost as heat while applying brakes.

The temperature of water at the bottom of a large waterfall is generally higher than that of the water at the top, because

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. the falling water absorbs heat from the sun

  2. the KE of the falling water is converted into heat

  3. the water at the bottom has greater PE

  4. rocks on the bed of the river give out heat

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Correct Option: B
Explanation:

Water is slightly warmer at the bottom of a waterfall than at the top because the gravitational potential energy is converted first to kinetic energy of the falling water, and finally to heat energy as it comes to rest at the bottom.

The temperature of water at the bottom of a waterfall is higher than that ofthe water at the top, because

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. falling water absorbs heat from the sun

  2. kinetic energy of the falling water is converted into heat

  3. water at the bottom has greater potential energy

  4. the rocks on the river bed give out heat

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Correct Option: B
Explanation:

When water falls from top of a waterfall, it has a force of friction being exerted on it due to which some of its kinetic energy gets converted into heat energy.

Thus the temperature of water at the bottom of waterfall is higher than that at the top.

A pendulum rocks back and forth. In an ideal setting, this motion would go on perpetually without loss of mechanical energy. Realistically, if you held a pendulum up and made it go in motion, it would slow to a stop.
What is responsible for the pendulum gradually losing mechanical energy? Ignore the mass of the string holding the pendulum bob in motion.

physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

  1. The work done by gravity

  2. The work done by tension

  3. The work done by air resistance

  4. The pendulum does not lose mechanical energy

  5. There is not enough information to determine the cause

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Correct Option: C
Explanation:

The vibrations of the pendulum die after some time , it is because of the frictional force of air which opposes the motion of bob .So air resistance is responsible for the loss in mechanical energy .