Mechanics

51.Energy is created on the Sun-
 
A. By nuclear fission
 
B. By nuclear fusion
 
C. By oxidation reactions
 
D. By reduction reactions
 
Option”B” is correct.
Solar energy is created by nuclear fusion that takes place in the sun. Fusion occurs when protons of hydrogen atoms violently collide in the sun’s core and fuse to create a helium atom. This process, known as a PP (proton-proton) chain reaction, emits an enormous amount of energy.
52.Sun’s energy is generated
 
A. By ionization
 
B. By nuclear fusion
 
C. By nuclear fission
 
D. By oxygen
 
Option”B” is correct.
Solar energy is created by nuclear fusion that takes place in the sun. Fusion occurs when protons of hydrogen atoms violently collide in the sun’s core and fuse to create a helium atom. This process, known as a PP (proton-proton) chain reaction, emits an enormous amount of energy.
53.dynamo converts
 
A. High voltage to low voltage
 
B. Electrical energy into mechanical energy
 
C. Mechanical energy into electrical energy
 
D. Low voltage to high voltage
 
Option”C” is correct
54.Which of the following is produced by the conversion of solar energy using photovoltaic cells?
 
A. Light energy
 
B. Electrical energy
 
C. Thermal energy
 
D. Mechanical energy
 
Option”B” is correct.
Solar-powered photovoltaic (PV) panels convert the sun’s rays into electricity by exciting electrons in silicon cells using the photons of light from the sun. This electricity can then be used to supply renewable energy to your home or business.
55.When we sit on a seat having a rubber mattress or lie down on the mattress, its shape changes. It is found in the substance
 
A. Kinetic energy
 
B. Potential energy
 
C. Stored energy
 
D. Fission energy
 
Option”B” is correct.

  • Potential energy-
    • ​It is stored energy that depends upon the relative position of various parts of a system.
    • Spring has more potential energy when it is compressed or stretched.
    • A steel ball has more potential energy raised above the ground than it has after falling to Earth.
    • Potential energy was included with kinetic energy as a form of mechanical energy so that the total energy in gravitational systems could be calculated as a constant.

Important Points

  • Kinetic energy-
    • ​It is a form of energy that an object or a particle has because of its motion. 
    • If work, which transfers energy, is done on an object by applying a net force, the object speeds up and thereby gains kinetic energy. 
    • It is a property of a moving object or particle and depends not only on its motion but also on its mass.
    • The translational kinetic energy of a body is equal to one-half the product of its mass, m, and the square of its velocity, v, or 1/2mv2.
  • Mechanical energy- 
    • It is a sum of the kinetic energy, or energy of motion, and the potential energy, or energy stored in a system because of the position of its parts.
    • Mechanical energy is constant in a system that has only gravitational forces or in an otherwise idealized system.
    • The mechanical energy of the system is diminished at the end of each swing by the tiny amount of energy transferred out of the system by the work done by the pendulum in opposition to the forces of friction and air resistance. 

56.Which of the following does not have kinetic energy
 
A. Bullet fired
 
B. Running water
 
C. Working hammer
 
D. Stretched bow
 
Option”D” is correct.

  • The stretched bow doesn’t possess kinetic energy.
  • It possesses potential energy as it is in a static position.
  • Since fired bullet, running water and working hammer are in motion, they possess kinetic energy.

57.When the speed of a moving object is doubled, its kinetic energy
 
A. Doubles up
 
B. Quadruples
 
C. Stuff stays
 
D. Triples
 
Option”B” is correct
58.Climbing a ladder requires more energy because-
 
A. Person does work against gravity
 
B. Person works against gravity
 
C. Person acts in the direction of gravity
 
D. Person does nothing
 
Option”B” is correct.
While climbing a ladder, potential energy is used by us because we uplift our body to the top of the ladder vertically upwards against the gravitational force with the help of our legs or using our legs
59.Which of the following laws justifies the statement that matter can neither be created nor destroyed?
 
A. Law of conservation of energy
 
B. La Chatelier’s law
 
C. Law of conservation of mass
 
D. Law of osmosis
 
Option”A” is correct.

Antoine Laurent Lavoisier stated the Law of Conservation of Mass. He stated that in a chemical reaction, the matter is neither created nor destroyed. The mass of the reactants is equal to the mass of the products.

60.The use of hydraulic brakes in self-propelled vehicles is actually a direct application of which law?
 
A. Pascal’s law
 
B. Torricelli’s law
 
C. Archimedes’ principle
 
D. Newton’s law
 
Option”A” is correct.
The correct answer is Pascal’s Law. The hydraulic brake used in automobiles is a direct application of Pascal’s Law. A typical application of Pascal’s principle for gases and liquids is the automobile lift seen in many service stations (the hydraulic jack)

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