Tag: physics

Questions Related to physics

Iron glows in red colour when it is heated to very high temperature because:

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

  1. Heat we supply consumes red colour at high temperature

  2. Mechanical energy is being converted into heat energy

  3. Light energy is being converted into heat energy

  4. Heat energy is being converted into light energy

Show answer
Correct Option: D
Explanation:

Iron glows in red colour when it is heated to very high temperature because heat being a form of energy can be transformed into other forms of energy.

A moving coin hits another coin and sets it into motion.In this case energy from the moving coin is ---- to the other coin:

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

  1. Flown

  2. Taken

  3. Not transferred

  4. Transferred

Show answer
Correct Option: D
Explanation:

The moving coin has kinetic energy initially, after hitting the other coin it transfers its kinetic energy to the other coin and sets it in motion.(In reality some part of energy is also lost as heat energy)

When a stone is thrown upwards:

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

  1. Kinetic energy increases and Potential energy decreases

  2. both Kinetic energy and Potential energy increase

  3. Kinetic energy decreases and Potential energy increases

  4. both remain constant

Show answer
Correct Option: C
Explanation:

When a stone is thrown upwards, its velocity decreases and height increases. 

$K.E. = \dfrac{1}{2}{ mv }^{ 2 }$
$P.E. = mgh$
Thus, its kinetic energy decreases and potential energy increases.

In which of the following, chemical energy is converted into heat energy?

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

  1. Heater

  2. Refrigerator

  3. Candle

  4. Motor

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Correct Option: C
Explanation:

The chemical present in the candle burns with oxygen to give out heat.

Which of the following statement is NOT true?

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

  1. State of rest of a body is same as the state of zero speed

  2. Human body converts chemical energy into muscular energy

  3. Water in river flows down due to its kinetic energy

  4. Liquids exert pressure on the walls of the container

Show answer
Correct Option: C
Explanation:

Option C is not correct because river flows down due to its gravitational potential energy.

In steam engine:

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

  1. Mechanical energy is converted to heat energy

  2. Heat energy is converted to mechanical energy

  3. Heat energy is converted to electrical energy

  4. Heat energy is converted to chemical energy

Show answer
Correct Option: B
Explanation:

Heat is used to generate steam which moves the pistons and thereby converting heat energy to mechanical energy.

A tube light converts electrical energy into :

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

  1. Chemical energy

  2. Magnetic energy

  3. Light energy

  4. Mechanical energy-

Show answer
Correct Option: C
Explanation:

A tube light converts $Electrical  \ energy$ to $Light  \ Energy$.

The device / machine which converts chemical energy into electrical energy is

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

  1. Electric bulb

  2. Electric motor

  3. Battery

  4. Solar cell

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Correct Option: C
Explanation:

Option A: Electrical bulb converts electrical energy into heat.

Option B: electrical motor converts electrical energy in mechanical energy.
Option C : battery converts chemical emergy into electrical energy.
Option D: solar cell converts light (using photons) into electrical energy.
So best possible answer is option C.

Which of the following statements is correct?

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

  1. Kinetic energy of a system can be changed without changing the momentum

  2. Kinetic energy of a system cannot be changed without changing its momentum

  3. Momentum of a system cannot be changed without changing its kinetic energy

  4. A system cannot have energy without having momentum

Show answer
Correct Option: A
Explanation:

Answer is A

Momentum is a vector quantity while K.E is a scalar quantity ,we can change velocity in such a way momentum remains same but K.E changes .

A solar water heater converts

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

  1. Light energy into heat energy

  2. Heat energy into light energy

  3. Chemical energy into heat energy

  4. Light energy into electrical energy

Show answer
Correct Option: A
Explanation:

Solar heater absorbs light, and thus photons of light are absorbed and the energy contained in them is converted to heat energy, which raises the temperature of water flowing slowly in contact with the plate and thus heat energy is transfered from plate to water.

Hence a solar heater converts light energy into heat energy.
Option A.