Question 1

Which of the following physical quantities is a scalar quantity?

Accepted Answer

Mass. Mass is a scalar quantity because it only has magnitude and no direction. It remains constant regardless of the object's position in the universe. In contrast, quantities like velocity and acceleration are vectors because they require direction.

Question 2

What is the SI unit of luminous intensity?

Accepted Answer

Candela. The candela is the SI unit used to measure luminous intensity in a given direction. It is one of the seven fundamental base units in the International System of Units. This unit helps in quantifying the brightness of light sources as perceived by the human eye.

Question 3

Who is credited with the discovery of the Law of Universal Gravitation?

Accepted Answer

Isaac Newton. Isaac Newton formulated the Law of Universal Gravitation in 1687. This law states that every mass exerts an attractive force on every other mass. He published these findings in his famous work titled Philosophiæ Naturalis Principia Mathematica.

Question 4

Which instrument is used to measure atmospheric pressure?

Accepted Answer

Barometer. A barometer is a scientific instrument used specifically to measure atmospheric pressure. It was invented by Evangelista Torricelli in the 17th century. Changes in atmospheric pressure measured by this tool are often used to forecast weather changes.

Question 5

The fundamental physical quantity 'Time' is measured in which SI unit?

Accepted Answer

Second. The second is the base unit of time in the International System of Units (SI). It is defined based on the fixed numerical value of the cesium frequency. All other time units like minutes or hours are derived from the second.

Physics Basics — Set 1