Railway Science (Physics-Work, Energy and Power) (Part-II)

Total Questions: 50

1. The potential energy of an object increases with its ______. [RRB Group D 10/10/2018 (Morning)]

Correct Answer: (b) height
Solution:

Potential energy is the energy stored in an object due to its position or configuration relative to its surroundings. The height of an object is directly related to potential energy, and an increase in height leads to an increase in potential energy.

2. The bullet fired from a gun penetrates deeply into the target because it has ________. [RRB Group D 10/10/2018 (Evening)]

Correct Answer: (d) kinetic energy
Solution:

It is the energy possessed by an object due to its motion. When a bullet is fired from a gun, it possesses kinetic energy because it is in motion. As the bullet travels through the air and strikes the target, this kinetic energy is transferred to the target, causing it to penetrate deeply.

3. The work done is zero if there is no _______. [RRB Group D 11/10/2018 (Morning)]

Correct Answer: (d) Displacement
Solution:

Work Done = Force × Displacement. Other Formulas - Power = Work/Time, Momentum = mass × Velocity, Velocity = Displacement/Time, Density = mass/Volume, Pressure = Force/Area, Energy = Power × Time.

4. Which of the following energy varies with the height of an object? [RRB Group D 11/10/2018 (Morning)]

Correct Answer: (d) Potential energy
Solution:

Potential energy = mgh. Where, m = Mass, g = acceleration due to gravity (9.8 m/s²) and h = Height. Kinetic energy = 1/2 𝑚𝑣² , where m = mass and v = velocity. Nuclear Energy - A form of energy released from the nucleus, the core of atoms, made up of protons and neutrons. Chemical energy - The energy which is stored in the bonds of chemical compounds (molecules and atoms).

5. Energy can neither be created nor destroyed, but it can be converted into one another. It is called __________ . [RRB Group D 11/10/2018 (Afternoon)]

Correct Answer: (b) Law of conservation of energy
Solution:

Law of conservation of mass: This distinct law states that the total amount of mass in an isolated system remains constant. Law of entropy: While related to energy and thermodynamics, this law describes the tendency of systems to move towards increasing disorder and decreasing energy availability.

6. The sum of kinetic energy and potential energy of an object is called _______ [RRB Group D 15/10/2018 (Morning)]

Correct Answer: (a) Mechanical energy
Solution:

Kinetic energy is the energy possessed by an object due to its motion, and it is given by the formula K.E = 1/2 mv², where m is the mass of the object and v is its velocity. Potential energy is the energy stored in an object due to its position. P.E = mgh, where ‘g’ is the acceleration due to gravity and ‘h’ is the height.

7. If a shot is fired from a gun and the gun comes backwards, what will be the kinetic energy of the gun ? [RRB Group D 16/10/2018 (Morning)]

Correct Answer: (d) Less than bullet
Solution:

The law of conservation of momentum: the sum of momenta of the two objects before collision is equal to the sum of momenta after the collision provided there is no external unbalanced force acting on them.

8. The ability of an object to do work, or the energy contained in an object, depends on ___________ . [RRB Group D 16/10/2018 (Morning)]

Correct Answer: (c) Position and condition of the object doing the work
Solution:

Energy: The capacity of doing work by a body is called its energy. It is a scalar quantity. The energy contained in an object or its ability to do work is determined by its position and condition, as well as its potential and kinetic energy.

9. 1 joule/second = ? [RRB Group D 16/10/2018 (Evening)]

Correct Answer: (c) 1 watt
Solution:

Watt is the SI unit of power. The rate of doing work or the rate of transfer of energy is called Power. In other words, one watt is equal to one joule per second.

10. Which of the following can neither be created nor be destroyed ? [RRB Group D 16/10/2018 (Evening)]

Correct Answer: (d) Energy
Solution:

The law of conservation of energy states that energy can neither be created nor be destroyed. Although, it may be transformed from one form to another. Forces can be applied, changed, or removed. Power : The rate of doing work or the rate of transfer of energy. Momentum is the product of mass and velocity of an object.