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Thread: Why is gravity a conservative force?

1. Why is gravity a conservative force?

If I move a ball from point A to point B...

A ----------> B

Net F of gravity is 0.... so why is it conservative?

(Yes physics moron)

2. bump

3. because delta PE does not change regardless of the path taken...

4. Ok so your net force=0 and we know that force=mass x gravity or force=mass x acceleration...we know that you moved the ball from point A to point B...the mass of the ball does not change therefore your mass is conserved. In terms of linear accleration then, your value is 9.8 m/s2 which is also the value of gravity since there is no friction involved...thus force=0 and gravity is conserved and it always is under normal circumstance

Ok so your net force=0 and we know that force=mass x gravity or force=mass x acceleration...we know that you moved the ball from point A to point B...the mass of the ball does not change therefore your mass is conserved. In terms of linear accleration then, your value is 9.8 m/s2 which is also the value of gravity since there is no friction involved...thus force=0 and gravity is conserved and it always is under normal circumstance
What if I drop the ball from A to B?

A
-
-
-
-
B

6. Gravity weakens the farther away something gets from a mass.

7. Originally Posted by MindZiper
What if I drop the ball from A to B?

A
-
-
-
-
B
Gravity is still conserved value is still 9.8 m/s2...think about it like this when i let something go (A) its going to just fall at a positive value at 9.8 m/s2 in the y direction...then if i throw it up your gravity is still the same at maximum height, the only thing changing is your velocity...so your force would be mass x acceleration again and masses are same yet again as well as gravity...everything conserved still (excluding small bits like sound energy and recoil loss and etc.)

8. Originally Posted by uranium3825
Gravity weakens the farther away something gets from a mass.
in such case where the mass such as the moon or earth acting on each other have a different gravitational pull.

9. How is net F of gravity 0?
Gravity is a constant force of 9.8m/s^2.

As for how it's conservative, look at potential energy formula : e = mass*g*height.
It's a conservative force because the work done only depends on the distance you move the object. There is nothing lost to heat, friction etc.

10. Originally Posted by tninetyman
How is net F of gravity 0?
Gravity is a constant force of 9.8m/s^2.

As for how it's conservative, look at potential energy formula : e = mass*g*height.
It's a conservative force because the work done only depends on the distance you move the object. There is nothing lost to heat, friction etc.
I think he meant to say the net force was 0.

11. Originally Posted by uranium3825
Gravity weakens the farther away something gets from a mass.
True, but an object like the earth is so huge, why are we not crushed by the gravity of the earth pulling us down. Its much bigger than us...yes even the really big people in the misc

Gravity is still conserved value is still 9.8 m/s2...think about it like this when i let something go (A) its going to just fall at a positive value at 9.8 m/s2 in the y direction...then if i throw it up your gravity is still the same at maximum height, the only thing changing is your velocity...so your force would be mass x acceleration again and masses are same yet again as well as gravity...everything conserved still (excluding small bits like sound energy and recoil loss and etc.)
So it should be, when Delta F = 0... its conservative?
Like me going down a slide... and then going back to the top (w/o friction)...

Why is friction non conservative then?
If you have a constant friction, there'll always be a force (friction). Going up or down the slide.

I think he meant to say the net force was 0.
The net force is only zero if you're doing a sum of forces with an object at rest.
Gravity on Earth is never zero.

14. Originally Posted by MindZiper
So it should be, when Delta F = 0... its conservative?
Like me going down a slide... and then going back to the top (w/o friction)...

Why is friction non conservative then?

Read above - gravity = conservative because there is no loss of energy to heat or friction.

So friction scrubs away energy when you are trying to do work. Like moving a box from rest on the ground, takes more energy than the mass would suggest, because some of your work is being lost to friction.

15. Originally Posted by MindZiper
So it should be, when Delta F = 0... its conservative?
Like me going down a slide... and then going back to the top (w/o friction)...

Why is friction non conservative then?
Your EF (sum of forces) is 0 when there is no friction and such...with friction you have to realize that it acts in the opposite direction...you going down the slide and then assuming you slide up (which is kinda weird to do) will also be EF=0 assuming everything was the same (including velocity, friction force, etc.)..so now youre formula will be F=(your mass)(accelaration due to gravity 9.8 m/s2) - friction force(angle of slope of slide if any)...so yes your gravity is still same...force force due to gravity is different

16. Originally Posted by tninetyman
The net force is only zero if you're doing a sum of forces with an object at rest.
Gravity on Earth is never zero.
Well true i had to kind of reread that the ball was originally at x=0 and then moved some so ya youre right the force is not 0.

17. because it keeps black people down

18. Originally Posted by tninetyman
Read above - gravity = conservative because there is no loss of energy to heat or friction.

So friction scrubs away energy when you are trying to do work. Like moving a box from rest on the ground, takes more energy than the mass would suggest, because some of your work is being lost to friction.
ah... so... if the force is constant and isn't "lost" to anything. its conservative.

air drag and/or friction lose "energy" to heat.

How is this different from me pushing a box non-stop? How am I losing energy there? (assuming no friction).

19. Originally Posted by MindZiper
ah... so... if the force is constant and isn't "lost" to anything. its conservative.

air drag and/or friction lose "energy" to heat.

How is this different from me pushing a box non-stop? How am I losing energy there? (assuming no friction).
If there is no friction then it would be conservative.
Unfortunately you have static and dynamic coefficients of friction. So a high static coefficient to get the box moving, but you still have dynamic friction which acts on the box as its moving.

20. Originally Posted by tninetyman
If there is no friction then it would be conservative.
Unfortunately you have static and dynamic coefficients of friction. So a high static coefficient to get the box moving, but you still have dynamic friction which acts on the box as its moving.
Then how does this differ to having a box between two walls (w/ friction)

Gravity pulls it down

|----|
|BOX|
|----|

Is gravity still conservative?
If so... what if there's no gravity and I'm pushing the box down... what happens then?

lol I'm sure this is like those stuff that its so easy... it's hard.

21. Originally Posted by MindZiper
Then how does this differ to having a box between two walls (w/ friction)

Gravity pulls it down

|----|
|BOX|
|----|

Is gravity still conservative?
If so... what if there's no gravity and I'm pushing the box down... what happens then?

lol I'm sure this is like those stuff that its so easy... it's hard.
I'm not sure...
Your rep power might jog my memory?

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