Energy Test - 3

According to the question the correct option will be ‘B’ because when the man moves on a horizontal surface, then work done by gravity is zero since gravitational force acts perpendicular to the displacement.

And the normal force will be also perpendicular to displacement so work done by It also is zero. - - - - - - - - 1

But frictional force is acting opposite to displacement so work done by frictional force is negative. - - - - - - - - - - - 2

Using statement (1) and (2) we can say that work done by contact force is non – zero.

According to the question the correct option will be ‘C’ because 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.

According to the question the correct option will be ‘C’ because Energy is produced in a star's center, where pressures are enormous and temperatures reach 27 million (15 million). 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.

According to the question the correct option will be ‘B’ because Any work done on a body changes in is potential energy, as we deduce from work energy theorem.

According to the question the correct option will be ‘B’ because S.I. unit of energy is N−m which is also known as joule and CGS unit of energy is Dyne−cm which is also known as erg.

and 1erg = 10−7J

So answer to the question is B.

According to the question the correct option will be ‘C’ because kilowatt is the unit of power.

Joule is the unit of energy (capacity to do work).

Newton- meter is the unit of work.

Kilowatt hour is the commercial unit of energy.

Hence the correct answer is option C.

According to the question the correct option will be ‘C’ because According to the question the correct option will be ‘C’ because Energy is defined as the ability to do work and its SI unit is Joule.