SCI-ART LAB

Science, Art, Litt, Science based Art & Science Communication

# Qs people asked me on science and my replies to them - part 246

Krishna: We don’t ‘believe in’ Newton’s laws. We trust them and accepted them because there is genuine evidence that they work.

Newton's laws of motion are three laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows (1):

Law 1. A body continues in its state of rest, or in uniform motion in a straight line, unless acted upon by a force.

Law 2. A body acted upon by a force moves in such a manner that the time rate of change of momentum equals the force.

Law 3. If two bodies exert forces on each other, these forces are equal in magnitude and opposite in direction.

Newton's laws were verified by experiment and observation for over 200 years, and they are excellent approximations at the scales and speeds of everyday life.

Now let us watch this video that shows Real life examples of the Three Laws of Motion

Isaac Newton’s three laws of motion explain how forces and solid bodies interact, including planets floating in the vacuum of space. His law of gravity describes how the masses of two objects creates an attraction between them that weakens with distance. Together, these scientific principles help explain the movements of the planets around the sun in our solar system.

Newton’s First Law of Motion states that a body in motion keeps the same motion unless acted upon by an outside force. Likewise, if it is not moving, it remains that way unless a force acts on it. Any moving object in space will travel in a straight line at the same speed forever, planets included. The planets would be moving in straight lines, but the sun’s gravity pulls them toward it. The force of gravity causes the moving planets to travel in roughly circular orbits around the sun. They have been circling the sun for billions of years because other forces have been too weak to change the orbits in any significant way.

In Newton’s Second Law of Motion, an object accelerates in proportion to the amount of force acting on it. If no force acts on the object, its velocity remains constant. The motion of the planets around the sun involves a constant acceleration. Here, however, acceleration means “changing direction” instead of “changing speed;” both are valid under the Second Law. The gravitational force exerted by the sun continually alters a planet’s path, bending it towards the sun although never directly at it.

The Third Law of Motion states that for every force acting on an object, another, equal force also acts in the opposite direction. For example, a cat sitting on a chair exerts a downward force on the chair from her weight; the chair also exerts a force on the cat, holding her up. In the same manner, the force exerted on a planet by the sun is also “felt” by the sun; however, because the sun is hundreds of times more massive than the planets, the force has barely any effect on the sun’s motion, although it affects the planet in a major way.

Newton’s Law of Gravity takes into consideration the masses of two objects and the distance between them. The strength of the gravitational force attracting the two objects together goes up as their masses increase and decreases as the distance increases. Gravity acts across even the enormous distances between the sun and outer planets. The mass of the sun and a planet create a force, pulling the planet’s orbit into a circle.

Newton's Third Law of Motion states that for every action there is an equal and opposite reaction. Newton's Second and Third Laws of Motion play a part in how a rocket lifts off. As the gas is expelled, the rocket is propelled with equal force in the opposite direction, once the force exceeds the weight of the rocket.

You can watch it in this video

So, we have evidence that Newton’s laws work. That is why we trust them and use them with confidence and success.

Never use the word belief when you are dealing with science. Science never asks you to believe in it blindly. Only when you are fully satisfied with what science says with evidence can you trust it. That is the beauty of science.

Footnotes:

Q: Does the bald head emit the light of knowledge or just reflect bright light?

Krishna: This question reflects cultural conditioning of the mind.

In some cultures people say bald heads are a sign of intellectualism.

Usually balding starts when you starts to age. And some men sound intelligent enough at this age where balding starts for people to connect them both.

But actually there is no connection between these two and it is a myth. A man’s intellectual level has nothing to do with his hair loss.

Baldness can be the result of heredity, hormonal changes, medical conditions or a normal part of aging. Anyone can lose hair on their head, but it's more common in men. Baldness typically refers to excessive hair loss from your scalp. Hereditary hair loss with age is the most common cause of baldness.

95 percent of hair loss in men is caused by androgenetic alopecia. This inherited trait that tends to give men (mostly) a receding hairline and a thinning crown is caused by genetic sensitivity to a byproduct of testosterone called dihydrotestosterone (DHT).

Male pattern baldness usually begins when a guy is in his 30's or 40's, but it can also happen during the teen years after puberty, although it is much less common.

Female pattern baldness is generally caused by an underlying endocrine condition or a hormone secreting tumour.

Now why do bald heads reflect light?

Bald head look is naturally shiny due to oil either applied to it or produced naturally by your skin. Your hair follicles naturally produce an oil called sebum. After shaving your head or losing hair, the glands that are responsible for producing sebum continue to produce this oil. Instead of giving your hair a natural shine, the oil is giving your scalp a shine.

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