Some Amazing Facts Collection

*********{Some Amazing Facts Collection}**********

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1.If an atom were the size of a stadium, its electrons would be as small as bees

2.Laser is an abbreviation of Light Amplification by Stimulated Emission of Radiation.

3.At 25, Physicist Lawrence Bragg is the youngest person to receive a Nobel Prize.

4.The effect of Relativity made Astronaut Sergei Avdeyev a fraction of a second younger upon his return to Earth after 747 days in space.

5.The amount of water beneath our ground soil is 50 times as much as all the water in the rivers and lakes combined.

6.The world's densest wood, the Black Ironwood (Olea laurifolia), does not float on water and therefore sinks

7.Due to the effect of Thermal Expansion, the Eiffel Tower is upto 15 cm taller in summer

8.After helium and hydrogen, the most common element on the Sun is oxygen

9.Boomerang Nebula is the coldest known place in the universe

10.The Moon is moving away from the Earth 3.8 cm every year.

 
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Numerical problem

A particle is constrained to move in a circle with a 10-meter radius. At one instant,the particle’s speed is 10 meters per second and is increasing at a rate of 10 meters per second squared. Find the angle between the particle’s velocity and acceleration vectors.

Solution:
There are two perpendicular components of acceleration.
1) at along the direction of velocity,that increase the speed. so, at=10m/s2
2)ac centripetal acceleration,towards the center of rotation . ac=v2r=10m/s2
So, net a⃗ =a⃗ t+a⃗ c
|ac|=|at|, so it's equally inclined(at 450) to both components.

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Classical Mechanics

An astronomer observes a very small moon orbiting a planet and measures the moon’s minimum and maximum distances from the planet’s center and the moon’s maximum orbital speed. Which of the following CANNOT be calculated from these measurements?

A. Mass of the moon
B. Mass of the planet
C. Minimum speed of the moon
D. Period of the orbit
E. Semimajor axis of the orbit
 

Solution:

Let m = mass of the moon and M = mass of the planet,

Here we can see that m cancels out so, there’s no way to calculate mass of the moon.
Answer: A

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