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1h
comment Does gravitational time dilation have a direction?
I don't think so. If you're experiencing zero force, you are in an inertial reference frame, meaning you are not accelerating and there is no time dilation. In other words, in an inertial reference frame, you age more than in any other frame (as a note, you'd have to accelerate at slightly less than 1g since gravity decreases with distance from Earth)
8h
comment Why do you believe in
@Duuur You may try philosophy.stackexchange.com or something similar. Science is about observation and prediction, not naming. Gravity by any other name would pull as hard.
8h
comment Find the period of a pendulum system
If you show some of the work you've already done, you might re-post to math.stackexchange.com
8h
comment What happens to the average kinetic energy if you double the temperature?
Just as a note, at some point simple kinetic energy will become rotational and vibrational energy (different forms of kinetic energy) for diatomic molecules.
8h
comment Does gravitational time dilation have a direction?
I think I'm misunderstanding. In your example, isn't the second observer experiencing zero net force/zero net gravity?
9h
comment Force required for balancing a three-bodied frictionless and gravityless system
At the very least, show us your calculations, even if they're wrong.
9h
comment Gravitational force between rod and mass $m$
As @BillN notes, the sphere is a special case that does not apply to other shapes. If you're very far away from an object, you can approximate the gravitational force as coming from its center of mass without too much loss of accuracy. However, that's another special case. Unless the object is a consistently-dense sphere (or spherical shell) or you are far away from it, you can not apply the center of mass simplification.
2d
comment Solving for diameter of a glass tube to hold water
OK, I missed the "surface tension" tag on your question. You're looking to see when gravity is stronger than the electrical force that binds water to glass (eg, resulting in a meniscus).
2d
comment Solving for diameter of a glass tube to hold water
Do you mean a water barometer of some sort?
2d
comment Gravitational force between rod and mass $m$
You're probably thinking of a sphere, where the gravitational attraction from outside of the sphere acts the same as a point mass at the center of the sphere. The same isn't true for other shapes, not even ellipsoids (as I recently found it when studying "surface normals").
Feb
7
comment Elastic collision / relative velocity problem
Random thought: in your final answer, is kinetic energy conserved (as it must be in an elastic collision)?
Feb
7
comment What are these cycles in orbital eccentricity called?
en.wikipedia.org/wiki/Orbital_eccentricity#Examples suggests your values for Earth's long-term eccentricity are a bit high: "Over hundreds of thousands of years, the eccentricity of the Earth's orbit varies from nearly 0.0034 to almost 0.058". As the article @dmckee links notes, VSOP theory can give you a fairly good idea of Earth's eccentricity, perihelion and aphelion: caglow.com/info/compute/vsop87
Feb
7
comment Relativity Mapmaking in spacetime
I think they mean: draw A at (0,0), draw B at (0,1). Then draw a circle of radius 3.161 from A and a circle of radius 2.0 from B. The two points where those circles intersect is where you can place C. Do something similar for D, but also make sure it's 2 units from C.
Feb
6
comment Why is there not always a force in the direction of motion?
An object in motion tends to remain in motion.
Feb
6
comment Bullet - Jet problem, How to equate horizontal displacement. projectile motion
You may want to re-ask this question on math.stackexchange.com, but do show some of your work, how far you got, where you are stuck, etc.
Feb
5
comment Find the angle of the projectile
I meant, the actual numbers you were given and the full statement of the problem.
Feb
5
comment Freely falling body applied some external force
Didn't notice this earlier, but 10m/s^2 isn't a velocity, it's an acceleration. Did you mean thrown with an upward velocity of 10m/s?
Feb
5
comment Find the angle of the projectile
At the very least, you'll have to show us your calculations.
Feb
5
comment Freely falling body applied some external force
As with your other question, how long is the 10N force applied?
Feb
5
comment A body thrown upwards with some external force
Yes, the amount of time or the amount of distance (force * distance = work).