Explanation

• Al-Biruni was a famous Muslim mathematician, astronomer, and geographer.
• He calculated the Earth's radius using trigonometric principles and measurements of the angle of dip from a mountain.
• His estimated radius was approximately 6,339.6 km, which was remarkably close to the modern mean radius of about 6,371 km.
• He lived from 973 CE to 1048 CE.

Last verified on 09-11-2026

Explanation

• Ibn al-Haytham is known as the Father of Modern Optics.
• He made groundbreaking discoveries about light and vision.
• His famous book is Kitab al-Manazir (Book of Optics).
• His research was done around 1011–1021 AD.

Last verified on 27-04-2026

Explanation

• The First Law of Thermodynamics is also known as the Law of Conservation of Energy.
• It states that energy can neither be created nor destroyed; it can only be transferred or transformed from one form to another.
• For example, an electric heater converts electrical energy into heat energy.
• The mathematical expression is Delta U = Q - W, where Q is heat supplied and W is work done by the system.

Last verified on 09-11-2026

Explanation

• The SI unit of force is the newton (N).
• 1 N = the force needed to accelerate 1 kg of mass by 1 m/s²
• Derived unit: N = kg·m/s²
• Named after Sir Isaac Newton
• Based on F = ma (Newton's second law)

Additional information:

1. The metre, unit of length — symbol m
2. The kilogram, unit of mass — symbol kg
3. The second, unit of time — symbol s

Last verified on 09-11-2026

Explanation

• Calcium (Ca) is an alkaline earth metal belonging to Group 2 of the periodic table.
• Its atomic number is 20.
• Mercury (Hg) is a liquid metal at room temperature.
• Its atomic number is 80.
• Mercury has a boiling point of approximately 356.7°C.

Last verified on 09-11-2026