Railway Science (Physics-Force and Pressure) (Part-II)

As we know, Work Done = Fs cosθ and cos 180° = -1. In this case, the force of gravity is acting in the downward direction. But, the displacement of the body is in the upward direction. Since the angle between the force and displacement is 180°, the work done by the gravitational force on the body is negative.

Average speed of a body in a certain time interval is the distance covered by the body in that time interval divided by time. So if a particle covers a certain distance s in a time t₁ to t₂ , then the average speed of the body is: vₐᵥ= s/t₂-t₁. Average velocity of a body in a certain time interval is given as the displacement of the body in that time interval divided by time.

Pressure is inversely proportional to area, if the area is less then the pressure will be more. Pressure: SI unit is Pascal. Formula: P = 𝐹𝑜𝑟𝑐𝑒/𝐴𝑟𝑒𝑎. Examples: Porters place a round cloth on their heads to increase surface area and reduce pressure.

Inertia refers to the resistance of any physical object to changes in its state of motion and is a parameter used to describe how the object's motion is affected by applied forces. Acceleration : This measures the rate of change of an object's velocity. Impulse : This is the change in momentum of an object.

It is a measure of the force applied perpendicular to the surface of an object per unit area. Mathematically, it is expressed as force divided by area (P =  𝐹/A).

By decreasing temperature and increasing pressure, the kinetic energy of gas molecules decreases and the intermolecular forces between them increase, respectively. On a hot day, air molecules have higher kinetic energy, increasing their tendency to escape into the surrounding environment (evaporation).

It represents the first equation of motion, which relates the final velocity (v), initial velocity (u), acceleration (a), and time (t). s = ut + 1/2 at² : It represents the position-time relation. It relates the displacement (s) to the initial velocity (u), acceleration (a), and time (t).

This is due to Newton's second law of motion, which states that force (F) equals mass (m) times acceleration (a). When lifting an object vertically, the acceleration due to gravity (g) acts downward, opposing the motion. Therefore, the net force required to lift the object is equal to its weight, which is the product of its mass (m) and the acceleration due to gravity (g).

The force acting on a body perpendicular to its surface is called thrust. Pressure is defined as the thrust acting over a unit area of the surface.