Physical Quantities and Measurement Test - 2

MKS units are based on meter, kilogram second (length, mass, time). Similarly for FPS (feet pound second) and CGS (centimeter gram second). But SI units include other quantities such as Temperature, Current etc. as well.

The magnitude of a physical quantity represent the amount contained in the quantity. Therefore, the magnitude of the quantity consists of a number only.

Percentage determines the accuracy in the measurement. More is the percentage of error, more is the error in the measurement.

Lux is the unit of illuminance or luminous intensity. The lux (symbol: lx) is the SI derived unit of illuminance, measuring luminous flux per unit area. It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface.

Ampere-hour is the unit of quantity of electricity or quantity of electric charge.

Power is measured in Watt.

Energy is measured in Joules.

Strength of current ia measured in Amperes.

Speed is defined as the ratio of distance covered to the time taken. The speed of a moving body is the distance travelled by it in unit time. If the distance is in km and time is in hours, then the speed is km/hr. If the distance is in m and the time is in seconds, then the speed is m/sec.

Speed  v = Distance / Time

Length and time are the fundamental quantities involved here to compare the speed of Ram and Shyam.

The pascal (Pa)(Pa) is the SI derived unit of pressure used to quantify internal pressure, stress, Young's modulus and ultimate tensile strength. The unit, named after Blaise Pascal, is defined as one newton per square metre.

Since z = ax + bx₂, unit of bx₂ must be that of zz.

Hence the unit of b is that of z/x²

which is km/h²

Light travels at approximately 300,000 kilometers per second in a vacuum, which has a refractive index of 1.0, but it slows down to 225,000 kilometers per second in water (refractive index = 1.3) and 200,000 kilometers per second in glass (refractive index of 1.5). The interaction of the light with the particles in the medius causes the delay.

Unit of g in SI is ms⁻¹ and that of G is Nm ² kg⁻²

Where 1 N = 1 kg ms⁻² (in MKS system)

So, MKS units of G is m³s⁻²kg⁻¹

Thus CGS unit of g is cm s⁻² and that of G is cm³s⁻²g⁻¹

Thus CGS unit of g/G is g cm⁻²