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

The energy stored in an object because of its specific shape or position. It is possessed by a body due to its height is called gravitational potential energy. The gravitational potential energy can be calculated as P.E = mgh.

Work is defined as the transfer of energy between a system and its surroundings through the application of a force over a distance. Positive work happens when the force applied to an object helps it move in the same direction as its displacement, transferring energy from the surroundings to the object. This increases the object's energy.

Other Physical Quantity and their Units with dimensional formula: Force - Newton (N = kg.m/s² ), [MLT⁻²]. Inductance - Henry (H), [𝑀𝐿²𝑇⁻² 𝐼⁻²].   Acceleration - m/s²  , [L 𝑇⁻²].  Magnetic Flux - Weber (Wb), [𝑀𝐿²𝑇⁻² 𝐼⁻¹].
Power - Watt (W), [𝑀𝐿²𝑇⁻³]. Pressure - Pascal (Pa = N/𝑚²), [𝑀𝐿⁻¹𝑇⁻² ].

Work is done only when a certain force is applied on an object and the object moves a certain distance in the direction of the applied force. Given, direction of applied force and the direction of motion of the object are perpendicular to each other; means θ = 90⁰ . Formula: Workdone = F × d × Cosθ . Since Cos90⁰ = 0, hence work done is Zero.

kinetic energy is directly proportional to the mass of the object and to the square of its velocity: K.E. = 1/2 × m × v², (where m - Mass of the body, v - Velocity). Its units of Joules (J) (One Joule = 1 kg m²s⁻²). Potential energy is energy that has the potential to become another form of energy. Formula - P.E. = mgh, (where m - mass, g - acceleration due to gravity, h - height in meters).

Other Examples of energy conversion from Potential to Kinetic forms - Hydroelectric Power: Water stored in a reservoir at a height has potential energy. When this water is allowed to flow downhill, its potential energy is converted into kinetic energy; Launching a Projectile: When you throw a ball upwards, it gains maximum potential energy at the highest point of its trajectory. As it falls back down, this potential energy is converted into kinetic energy.

The work done by the force is defined to be the product of the component of the force in the direction of the displacement and the magnitude of this displacement. Work done = F × d × Cosθ .

The kinetic energy of an object is the form of energy that it possesses due to its motion. The SI unit is joule (j). Examples of kinetic energy at work - A person walking, a soaring baseball, a crumb falling from a table and a charged particle in an electric field.

Work is said to be done when force is applied on an object and it gets displaced from its initial position. SI unit of work is Joules. Work done by a force acting on an object is equal to the magnitude of the force multiplied by the distance moved in the direction of the force.

Kinetic energy (KE): It can never be negative. Even if an object is moving very slowly, it will still have some kinetic energy. Formula: KE = 1/2 × m × v² . Potential energy (PE): It depends on the position of an object relative to a reference point and the forces acting on it. It can be positive, negative, or zero.