45 Answered Questions for the topic Gravity
Is it possible for two black holes to collide perfectly?
If two blackholes with exactly the same mass, are traversing the universe on a perfect collision course with no other gravitational force effecting either black hole, what would happen to both... more
Why shouldn't gravity be a force?
Why shouldn't gravity be a force? I am interested to know the reasons why we shouldn't treat gravity as a force in, for example, General Relativity. Won't we be able to model it accurately by... more
What physical forces pull/press water upwards in vegetation?
Each spring enormous amounts of water rise up in trees and other vegetation. What causes this stream upwards? Edit: I was under the impression that capillary action is a key factor: the original... more
When a ball is tossed straight up, does it experience momentary equilibrium at top of its path?
This question has been asked many times all over the Internet and answers can be found on places such as yahoo and ask.com, but I'm not satisfied with those answers and I don't trust the validity... more
Sandstone getting soaked with water?
I have seen someone putting a sandstone in water. With only about 10% of the stone sitting in the water. One could see the stone getting soaked with water. So there must be a force, which lets the... more
Does the mass of a star change as it collapses into a black hole?
I know (I think!) that when a really big star collapses on itself it creates a black hole. My question: When a star collapses, is the mass equal to the mass of the star when it's not a black hole?... more
Planet orbits: what's the difference between gravity and centripetal force?
My physics teacher says that centripetal force is caused by gravity. I'm not entirely sure how this works? How can force cause another in space (ie where there's nothing). My astronomy teacher... more
Origin of the force of gravity?
Where does exactly gravity come from when bodies exert this force? Does it come from the center of every object or it arises from their surface?
GR and my journey to the centre of the Earth?
>> [General Relativity] basically says that the reason you are sticking to the floor right now is that the shortest distance between today and tomorrow is through the center of the... more
Short of collision, can gravity itself kill you?
Imagine that you are falling into object with huge gravity (i.e. black hole) that does not have any atmosphere. The question is - before you hit the ground, can the gravity itself (which would be... more
How exactly does curved space-time describe the force of gravity?
I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or... more
Am I attracting Pluto?
My question is simple: as the title says, **am I exerting a force over for example Pluto**, although it is a **very small** force, it is there, right? Or maybe let's go further: **Am I exerting a... more
Does gravity differ from place to place on Earth?
Does a particular object have the same weight on every part of Earth or does it vary?
If gravity isn't a force, then why do we learn in school that it is?
I have studied some of Einstein's Theory of General Relativity, and I understand that it states that gravity isn't a force but rather the effects of objects curving space-time. If this is true,... more
The gravitational force, F, between an object and the earth is inversely proportional to the square of the distance from the object and the center of the earth. If an astronaut weighs 213 pounds on... more
Why is the Moon considered the major cause of tides, even though it is weaker than the Sun?
You have likely read in books that tides are mainly caused by the Moon. When the Moon is high in the sky, it *pulls* the water on the Earth upward and a high-tide happens. There is some similar... more
Was eintien agree with Newton's gravity
About gravity of Newton
A planet is orbiting a star when the star’s gravity suddenly vanishes. The planet thenheads outward along a straight line. Is Kepler’s second law still obeyed?
A planet is orbiting a star when the star’s gravity suddenly vanishes. The planet then obeys Newton’s First law and heads outward along a straight line. Is Kepler’s second law still obeyed? That is... more
The amount of gravitational potential energy of a Rocket (4U Physics)
2. A 222 kg weather rocket reaches its maximum height 32 km above the Earth's surface. Determine:a)The amount of gravitational potential energy at its maximum height.b) Its speed when it hits the... more
Planet X has three....
Planet X has three Earth's mass and twice times Earth's radius. The magnitude of the gravitational field near Planet X's surface is most nearly... a. 2 m/s^2 b. 7 m/s^2 c. 10m/s^2 d. 20... more
Finding mass of a star in orbit around a mass
In a certain binary star system, the masses of the two stars are equal. They revolve in a circular orbit around a center of mass midway between them. The orbital speed of each star is 2.8 x 10^5... more
Concept questions for gravity
Using the force of gravity, centripetal force, and normal force; why does an astronaut on a space station appear to be weightless?
How can an astronaut weigh different amounts when in different locations?
its about gravity and space
A mass of 1 kg is falling freely. the force of gravity is?
Force of gravity acting on a free falling body of mass 1kg?
If the force of gravity acts on all bodies in proportion of their masses, then why does not a heavy body fall faster than a light body?
This is question of gravity