Explanation

The Earth's Moon has considerably less mass than the Earth itself.

Not only is the Moon smaller than the Earth, but it is only about 60 percent as dense as Earth.

Thus, the gravitational attraction on the Moon is much less than it is here on Earth, and a person weighs less on the Moon.

ND20-1-2023

Explanation

The force of friction opposes the motion of an object, causing moving objects to lose energy and slow down.

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ND18-1-2023

Explanation

Brewster’s angle is the angle of incidence at which light with a particular polarization is perfectly transmitted through a surface with no reflection.

At this angle, the reflected and refracted rays are perpendicular (90° apart).

Explanation

The speed of sound in a gas is proportional to the square root of temperature (in Kelvin):

v ∝ √T

If the temperature becomes 16 times, then:

New speed = √16 × original speed = 4 × original speed

Explanation

 A LASER beam can be sharply focused because it is highly coherent. 

Coherence refers to the well-organized nature of light waves in a laser beam, where all the waves are in phase with each other, allowing them to be concentrated into a small, focused spot

Explanation

Explanation

The substance reduces to (1/16) = (1/2)^4 of its original mass.  

This means 4 half-lives = 40 days  

So, 1 half-life = 40 / 4 = 10 days  

Explanation

• Heat is a form of energy associated with the motion of molecules in a substance.
• As molecules vibrate, rotate, and collide, they transfer energy from one another, resulting in the sensation of heat.

Explanation

• Earth is the biggest of all the terrestrial planets.
• It has temperature, weather, atmosphere and many other factors.
• Its surface 30% is covered with land and 70% with water.
• It has only one moon called Luna.

Explanation

Nuclear fusion is a process where two or more light nuclei (atomic nuclei with a small number of protons and neutrons) combine to form a single, heavier nucleus.

This process releases energy, as the resulting nucleus has a higher binding energy than the original nuclei.