Tag: physics

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Questions Related to physics

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

The energy generated in stars is because of

  1. radioactivity

  2. nuclear fission

  3. nuclear fusion

  4. photo electric phenomenon
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Energy is produced in a star's center, where pressures are enormous and temperatures reach 27 million°F (15 million°C). This causes nuclear fusion—atoms of hydrogen are ripped apart and fuse (join) to form helium. These reactions release vast amounts of energy, which makes the star shine.

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

What will be the potential energy of a body of mass 5 kg kept at a height of 10 m ?

  1. 50 J

  2. 0.5 J

  3. 500 J

  4. 25 J
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Answer is C.

Potential energy is energy stored in an object. This energy has the potential to do work. Gravity gives potential energy to an object. This potential energy is a result of gravity pulling downwards. The gravitational constant, g, is the acceleration of an object due to gravity. This acceleration is about 10 meters per second on earth. The formula for potential energy due to gravity is PE = mgh. As the object gets closer to the ground, its potential energy decreases while its kinetic energy increases. 
In this case, a body of mass 5 kg kept at a height of 10 m. So the potential energy is given as 5 * 10 *10 = 500 J.
Hence, the potential energy of a body of mass 5 kg kept at a height of 10 m is 500 J.

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

1 kilowatt hour $=$ ___________ .

  1. $10.6 \times 10^6$Joule
  2. $3.6 \times 10^6$Joule
  3. $30.6 \times 10^6$Joule
  4. $3.6 \times 10^5$Joule
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The kilowatt hour is a unit of energy equal to 1,000 watt-hours, or 3.6 megajoule. If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time in hours.
1 kilowatt hour $= 1000 \times 3600 joule = 3.6 \times 10^{6}\ J$

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

The capacity of a body to do work is called ______ .

  1. Stamina

  2. Potential

  3. Velocity

  4. Energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Energy is the capacity of a physical system to perform work. Energy exists in several forms such as heat energy, kinetic or mechanical energy, light energy, potential energy, electrical energy, or other forms. According to the law of conservation of energy the total energy of a system remains constant, though energy may transform into another form.
The SI unit of energy is the joule (J) or newton-meter (N-m). Joule is also the SI unit of work.