Railway Science (Physics-Units and Measurements)

Autometer - A small device inserted in a photocopier to enable the process of copying to begin and to record the number of copies made. Tachometer (RPM gauge) - An instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. Speedometer - An instrument that indicates the speed of a vehicle.

It was discovered by Leon Battista Alberti. Hygrometer - Measuring the humidity (Amount of water vapour in the air). Udometer - an instrument used to gather and measure the amount of liquid precipitation over a predefined area, over a period of time.

Decibel (a relative unit of measurement equal to one tenth of a bel). The pascal (Pa) is the SI unit of pressure. One pascal is equivalent to 1 newton (N) of force applied over an area of 1 square meter (m²). Joule - SI unit of work or energy.

Seismographs - Record the motion of the ground during an earthquake. An earthquake is the shaking of the surface of the earth resulting from a sudden release of energy in the earth's lithosphere that creates seismic waves.

Energy is the capacity for doing work. Joule - A unit of work or energy in the International System of Units, It is equal to 10⁷ ergs.

It works on the basis of laws of reflection of light. It consists of an outer case with mirrors at each end at 45° angle. Microscope - An instrument that produces enlarged images of small objects. Endoscope - A medical device with a light attached. It is used to look inside a body cavity or organ. Telescope - A device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation.

A light-year is the distance light travels in one Earth year. One light year = 9.46 × 10¹² km. Light moves at a velocity of about 300,000 kilometers (km) per second. The sunlight takes exactly 8.3 minutes to reach the surface of the earth. Fundamental Units: Length (meter), Mass (Kilogram), Time (second), Electric current (ampere), Temperature (Kelvin), Luminous intensity (Candela), Amount of substance (Mole).

A seismograph (seismometer) - An instrument used to detect and record earthquakes. A barograph is a barometer that records the barometric pressure over time in graphical form. A polarimeter is a scientific instrument used to measure the angle of rotation caused by passing polarized light through an optically active substance.

Stroboscope - Instrument used to create the illusion of slow or stopped motion by flashing a bright light at regular intervals. Stethoscope is an acoustic medical device for auscultation, or listening to internal sounds of an animal or human body. Spectroscope - Instrument used to analyze the spectrum of light emitted or absorbed by a substance.

Force is a push or pull on an object that causes a change in its position. Dimension: [MLT⁻²].