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Motion under gravity

When two bodies of two different weights(ex..an elephant n a boy) falling from certain height.. Both reaches the ground at the same time because gravity is independent of mass…but when we leave a leaf n a coin from a certain height coin reaches the ground first why?

Asked Harshith

It is the air resistance which plays the VILLAIN’s role here. The leave is affected more by the air resistance than the coin. In other words the magnitude of force exerted by gravity on ball is much greater than buoyant force and air resistance in the case of the coin whereas in the case of a leaf, the air resistance and buoyant force is comparable to its weight.

If these are dropped in a vacuum chamber, both will fall together and will take the same interval of time to reach the ground when dropped from the same height.

Please refer to the following videos

 

 

Gravity at different places on earth

The centre of earth is equator and if equator is the centre of earth and as we know the gravity is maximum at centre of the earth then why the gravity is less there?

Asked Aishwarya

Answer:

(Evidently, the question is posted out of some misconception or confusion)

Centre of earth means the centre INSIDE THE EARTH, and there the value of g is zero.

At the equator, the distance from the centre is maximum and therefore g is the minimum. Further, the effect of rotation is maximum at the equator as the distance of any particle on the surface is farthest from the axis of rotation at the equator and any object at the equator requires maximum centripetal force which is derived from the gravitational force of earth. Thus in both ways, g is minimum at the equator.

Gravity and something more

Jihin Asked:

Some Things That I Have Always Wondered OF : (i hope it may be answered soon …)
1)is it possible that our human body can withstand pressures twice or more than the atmospheric pressure without a suite or is there any artificial instruments or means in which our heart can be made to pump into a level in which we can attain this ability !!!
2)when more gravity  is experienced , it is said that time travels slowly – is it  relative ??? caz time goes at a constant rate !!! it is only the position or view that makes the observer feel the situations ???
3) Is there any gravity chambers successfully made out … in which the gravity can be changed accordingly to observe diff. phenomena ??? Cant It be possible to do that ????

Ans:

To be posted soon.

However, I agree that I may not be able to give you a satisfying answer to all your queries, as “Science says the first word of everything and the last word of nothing.” We are learning new things everyday. When we explore more and more, we find that we know less and less and our knowledge is too meagre.

By the time I prepare a well fitting answer to this, visitors are also requested to respond to the question by posting answers and comments.

Defy gravity

Athira asked:

HOW FAST  WOULD THE EARTH HAVE TO ROTATE SO THAT IT WOULD NEUTRALIZE GRAVITY?

A question from Gravitation.

Prince Patel Asked:

“Sun have high gravitational energy ,then why planets of solar system doesn’t colloid with sun?”

Answer:

“The planets are moving around the sun and the gravitational force is used in providing the necessary centripetal force (The force required by a body to move in a circular path). As long as the planets are in motion, they will not move towards the sun. A similar explanation hold good for moon going around earth also.”

Weight and inertia on moon

Say True or False; An object on the Moon weights 1/6 of what it weights on the Earth. Therefore, the object has less inertia on the Moon.( Justify your answer)

Answer: The statement is false.

Inertia depends on mass and not on weight. The weight on moon is less not because of a decrease in mass, but due to the decrease in the acceleration due to gravity on the surface of moon.

Inertia depends on mass and there is no change in mass when a body is taken to moon. Therefore the inertia of a body is same on moon as that on earth or anywhere else in the universe, even in a gravity free space.

Gravity on moon

We know that the first man to walk on moon was Neil Armstrong. it is said that there is  no force of gravity on moon. then how did Neil Armstrong moved a few steps on moon?

(Saranya asks)

Answer:

Who says there is no gravity in moon?

The acceleration due to gravity on moon is 1/6 that on earth.

I feel that you are confused by the concept of weightlessness in satellites.

On moon, it has its own gravity which is one sixth that on earth.

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  • Post Edited: Work done and Kinetic/Potential Energy https://t.co/53bHeenlkr
    about 2 days ago
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