set 1 MCQ Questions & Answers Detailed Explanation

Answer: (a)

A dimensionless quantity (also known as a bare, pure, or scalar quantity as well as a quantity of dimension one).

It is a quantity to which no physical dimension is assigned, with a corresponding SI unit of measurement of one (or 1), which is not explicitly shown. Dimensionless quantities are widely used in many fields, such as mathematics, physics, chemistry, engineering, and economics. Dimensionless quantities are distinct from quantities that have associated dimensions, such as time (measured in seconds).

Dimensionless units are dimensionless values that serve as units of measurement for expressing other quantities, such as radians (rad) or steradians (sr) for plane angles and solid angles, respectively. For example, the optical extent is defined as having units of metres multiplied by steradians.

Answer: (b)

1. CGS - centimetre-gram-seconds

The centimetre–gram–second system of units (abbreviated CGS or cgs) is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time.

2. SI - standard international system

S.I system (standard international system). In this system, the units of mass, length and time are the same, as that of the M.K.S system. However, it is an enlarged system encompassing all fundamental units.

3. MKS - metre-kilogramme-second

THE M.K.S. (metre-kilogramme-second) system of units is increasingly being. used by electrical engineers, particularly by those concerned with light-current and microwave work. The adoption of this system into the technical communications of physics and electrical engineering varies considerably.

4. FPS - foot-pound-second

The foot-pound-second (fps) system of units is a scheme for measuring dimensional and material quantities. The fundamental units are the foot for length, the pound for weight, and the second for time. The fps system has two variants, known as the American version and the Imperial version.

Answer: (a)

Since displacement is always less than or equal to distance but never greater than distance.

Hence, the numerical ratio of displacement to the distance covered is always equal to or less than one.

Answer: (c)

Light-year is the distance light travels in one year.

Light zips through interstellar space at 186,000 miles (300,000 kilometres) per second and 5.88 trillion miles (9.46 trillion kilometres) per year.