Gravity

[Akash Kagi]

Hello everybody,

 

Today is my first day on science forum. I am studying in 9th std. I came upon the following question in my text book, which I was unable to answer. So I am posting this on the scince forum, seeking your help. The question is-

"During which situation may an object dropped from a certain height not fall to the earth?"

 

Thanks and regards.

[swansont]

What have you come up with so far?

[Akash Kagi]

What have you come up with so far?

 

Thanks Swansont,

 

For your kind attention. Basically, I have not understood the question itself.

 

The question comes under the section ACCELERATION DUE TO GRAVITY

It reads as under-

Objects thrown vertically upwards move for a certain distance and then fall back to the ground. It is due to the gravitational force of the earth.

 

Every particle of matter in the universe attracts every other particle.

 

The credit proving this, stating the universal law of gravitation and inventing the method of calculating gravitational force goes to Sir Isaac Newton.

 

A body accelerates if and only if the resultant of all the forces acting on it is not equal to zero.

 

Does a body falling towards the ground accelerate due to gravitational force?

 

 

And then in a box with the heading THINK IT OVER the question is given.

[swansont]

So an object thrown vertically, or dropped from rest, with no additional forces acting on it, must hit. What if the extra conditions were not true?

[Akash Kagi]

So an object thrown vertically, or dropped from rest, with no additional forces acting on it, must hit. What if the extra conditions were not true?

 

Which extra conditions?

[michel123456]

Maybe the word "dropped" is misleading.

[swansont]

Which extra conditions?

 

The things I've italicized.

[michel123456]

Can you ask a 17 year old to think like Newton?

[swansont]

Can you ask a 17 year old to think like Newton?

 

I don't think I am. I'm asking someone to think like any other physics student.

[michel123456]

I don't think I am. I'm asking someone to think like any other physics student.

 

My post was not about you. You are trying to help very kindly.

[Anilkumar]

Thanks Swansont,

 

For your kind attention. Basically, I have not understood the question itself.

 

The question comes under the section ACCELERATION DUE TO GRAVITY

It reads as under-

Objects thrown vertically upwards move for a certain distance and then fall back to the ground. It is due to the gravitational force of the earth.

 

Every particle of matter in the universe attracts every other particle.

 

The credit proving this, stating the universal law of gravitation and inventing the method of calculating gravitational force goes to Sir Isaac Newton.

 

A body accelerates if and only if the resultant of all the forces acting on it is not equal to zero.

 

Does a body falling towards the ground accelerate due to gravitational force?

 

 

And then in a box with the heading THINK IT OVER the question is given.

 

Hi everybody,

 

I am trying to help Akash Kagi, but I am not sure, if I am right.

 

I think the context gives an indication to the answer.

 

"A body accelerates if and only if the resultant of all the forces acting on it is not equal to zero."

 

So the answer to the question -

"During which situation may an object dropped from a certain height not fall to the earth?"

may be;

 

A "situation" where the object which is droped [or whatever] is being acted upon by another force counter to the gravity, such that the net resultant force is zero- and so it does not fall to the earth. Something like a GLIDER may be an example.

 

Thank you.

[Twinbird24]

Aren't objects in low earth orbit (LEO), or orbits in general, also examples of objects that are "dropped" but don't fall back down to earth?

[swansont]

Aren't objects in low earth orbit (LEO), or orbits in general, also examples of objects that are "dropped" but don't fall back down to earth?

 

Something "dropped" from them would be.

[36grit]

Hello everybody,

 

Today is my first day on science forum. I am studying in 9th std. I came upon the following question in my text book, which I was unable to answer. So I am posting this on the scince forum, seeking your help. The question is-

"During which situation may an object dropped from a certain height not fall to the earth?"

 

Thanks and regards.

 

 

My guess, The situation that causes the object to burn up in the atmosphere.

[insane_alien]

if its horizontal velocity is greater than or equal to orbital velocity and it is high enough for atmospheric drag to be negligble

[michel123456]

Not acceptable answers are ( I think so):

 

1. when the dropped object is lighter than air.

2. when the object is a sheet of paper & you drop it in the center of a hurricane.

3. when the object is a bird.(a living one)

4. when the object is an airplane.(with pilot)

5. when the object is a helicopter.(see before)

6. when the object is dropped from a ship (it will fall to sea and not to earth, there is a capital letter missing at earth)

7. when the object is dropped on Mars. (after correcting the capital)

8. ...?

[D H]

See posts #12 and #13.

[rigney]

See posts #12 and #13.

 

When we can differeantiate the effects of something being dropping on earth as compared to being dropped on a "pulsar", perhaps better answers will be coming.

[D H]

Post #12/#13 is almost certainly the answer the teacher was looking for.

Edited January 8, 2011 by D H

[chinmayrshah]

The probable answer can be that when the object doesn't experience the gravity i.e. in space (condition: outside Earth's gravity field), the object won't be dropped". It will remain wherever it is. But again it

 

is something not the answer for a 17year student. He needs to know what are the forces acting on the body.

 

The other thing can be that a body, here say an empty mug of water, when submerged in a bucketful of water and forcibly pushed down, will comeback with a bounce due to equivalent buoyant force. But

 

again it is not dropping of an object. But yes, when certain force counterbalancing gravity, can make the object remain afloat or atleast might not allow the object to fall.

 

Comments and reviews are highly welcomed as I am new too!

 

 

 

Chinmay

[D H]

The probable answer can be that when the object doesn't experience the gravity i.e. in space (condition: outside Earth's gravity field), the object won't be dropped".

The homework is well past due (this thread is three weeks old now), so the answer can be given. Something orbiting the Earth such as an artificial satellite or the Moon is not outside Earth's gravity field. The best way to look at an orbiting body is that it is perpetually falling toward the Earth.

 

I missed insane_alien's post #15. That is just about spot-on. This is something a 17 year old in AP physics should be able to answer.

Edited January 15, 2011 by D H