Does Earth's Gravity Do Work on Satellites?

  • Thread starter Thread starter putongren
  • Start date Start date
  • Tags Tags
    Satellites Work
AI Thread Summary
In a perfect circular orbit, Earth's gravity does not do work on satellites because the gravitational force is always perpendicular to the displacement of the satellite. This perpendicular relationship means that the dot product of the gravitational force and the displacement vector is zero, resulting in no work being done. Since both potential and kinetic energy remain constant in such an orbit, there is no energy transfer involved. Therefore, the conclusion is that gravity does not perform work on satellites in a stable circular orbit. Understanding this concept is crucial for analyzing orbital mechanics.
putongren
Messages
124
Reaction score
1
Does the gravity of Earth do any work on satellites orbiting the planet, assuming perfect circular orbit?

General Definition of work: W=(line integral) F * ds , F=force vector, ds=infinitesimal displacement vector, *=dot product.

We know that in circular motion, the velocity vector is always perpendicular to the centripetal acceleration (I think we assume that centripetal acceleration is equated to gravitational acceleration), so 0 = F * v for all positions. so that means that 0 = F * ds/dt. If F * ds =0 for all positions, then W = 0. Does 0 = F * ds/dt imply F * ds = 0?

Thank you.
 
Physics news on Phys.org
Correct.
 
putongren said:
Does the gravity of Earth do any work on satellites orbiting the planet, assuming perfect circular orbit?
Perfect circular orbit means: potential energy doesn't change and kinetic energy doesn't change so there is no work to do.
 

Thread '1:1 versus 2:1 Mechanical Advantage debate'

The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
View full post »

Thread 'Newton's first law?'

Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
View full post »
Thread 'Beam on an inclined plane'

Thread 'Beam on an inclined plane'

Hello! I have a question regarding a beam on an inclined plane. I was considering a beam resting on two supports attached to an inclined plane. I was almost sure that the lower support must be more loaded. My imagination about this problem is shown in the picture below. Here is how I wrote the condition of equilibrium forces: $$ \begin{cases} F_{g\parallel}=F_{t1}+F_{t2}, \\ F_{g\perp}=F_{r1}+F_{r2} \end{cases}. $$ On the other hand...
View full post »

Similar threads

B To displace the Earth from its orbit
Replies
20
Views
2K
Work energy theorem problem -- Block sliding up a curved incline
Replies
10
Views
1K
Accelerating a satellite in a circular orbit
Replies
24
Views
3K
The satellite and its work done
Replies
2
Views
1K
B Why is speed constant when centripetal acceleration is constant?
Replies
24
Views
3K
Why the work done is coming out to be positive?
Replies
9
Views
1K
Constant velocity in a central force field
Replies
18
Views
1K
B Why do we feel gravitational acceleration from the Earth and not from the Sun?
Replies
5
Views
2K
Why do conservative forces try to reduce potential energy?
Replies
3
Views
2K
I Remark on centrifugal force in Heino Falcke's black hole book
Replies
22
Views
3K

Hot Threads

Recent Insights

Back
Top