Tagged Questions
-4
votes
0answers
30 views
Is Gravity a Push force? [duplicate]
I am not a Science graduate, so may be I have an unclear concept. but one thing keeps coming to my mind so I thought to discuss here with someone interested in Gravity.
Here I go: "I feel there is NO ...
0
votes
1answer
42 views
Calculate magnitude of force acting on some area by falling object
I have simple question: is it possible to calculate magnitude of force acting on some area by falling object?
Let's say I have an object with mass $5\text{ kg}$. I drop that object in height 1 ...
-4
votes
0answers
32 views
Basic force in gravity responsible for attracting everything including nonmetal [closed]
Why do things get attracted? It is said that there is a magnetic field around the earth, but how can the attraction of non-metals be explained in terms of magnetic fields?
How can one generate this ...
0
votes
1answer
38 views
Equilibrium and Torque [closed]
How does one calculate the forces that exert on a wooden board held by two trestles if one knows the weight of the board as well as the distance of both trestles?
-2
votes
2answers
106 views
Repulsion does not exist; Gravity assist slingshot as a repulsive force [closed]
unification theory might say that there is only one force in universe that is called gravity(attraction).
So at atomic level for same charges that repel eachother(electrons etc.), if thought of as a ...
13
votes
6answers
668 views
Why do we still need to think of gravity as a force?
Firstly I think shades of this question have appeared elsewhere (like here, or here). Hopefully mine is a slightly different take on it. If I'm just being thick please correct me.
We always hear ...
0
votes
0answers
20 views
Some basic questions about electric field & nucleus [duplicate]
I am not good in physics.You can say I am beginner in this field.
I have some basic questions.
I ju st want to know that
[1] If there is repulsive force between same charges proton-proton then why ...
0
votes
1answer
96 views
Energy needed to lift and bring down an object
A mass of 0.5 Kg needs to be moved from point A to another point (B) which is 1 meters above point A. The time for this movement should be 0.2 seconds, then the mass is kept at position B for another ...
0
votes
3answers
390 views
Force inversely proportional to the squared distance
Newton's law of universal gravitation:
"Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to ...
0
votes
1answer
67 views
Do all forces act in the same way where gravity is close to zero?
Suppose that I put in the outer space (where gravity from other bodies is negligible) a large, perfectly round sphere totally filled with water. At the bottom (even though "bottom" doesn't make much ...
2
votes
1answer
78 views
Vertical Load Reactions On A Ramp
Hello,
I'm working on a small hardware project.
I have two load sensors located at distance $S_1$ ($x=0$) and $S_2$. Assuming we ignore the weight of the ramp ...
What is the load on $S_1$ and ...
4
votes
2answers
141 views
Is Brian Cox right to claim that Gravity is a strong force for large masses, is it wrong, or is it only a matter of interpretation?
I watched a program of his in which it was claimed that since mass bends space in accordance to General Relativity, then in the case of very large stars it becomes a strong force to the point of being ...
6
votes
3answers
240 views
Tidal force on far side
I have a question about tidal forces on the far side of a body experiencing gravitational attraction from another body.
Let's assume we have two spherical bodies $A$ and $B$ whose centers are $D$ ...
3
votes
6answers
652 views
Do you feel gravity?
I have been reading a few articles about the question why we don't feel/notice gravity in everyday life, but I couldn't understand why exactly we don't feel/notice it, that is, why we don't feel a ...
0
votes
1answer
82 views
Nothing escapes BHs, gravitons mediate gravity, so why do BHs gravitate? [duplicate]
Possible Duplicate:
How does gravity escape a black hole?
Nothing escapes black holes, gravitons mediate gravity, so why do black holes gravitate?
My question is, "where is the hole (no ...
3
votes
2answers
109 views
Playground of Forces
Why is it that the gravitational force acts on large sized objects while the strong and weak nuclear forces act at subatomic levels only? What is that stops each other to enter each others domain?
0
votes
1answer
190 views
Understanding the math behind a falling object attached to a parachute
I'm trying to understand the mathematics behind calculating the total speed and force of a $40 kg_f$ object hooked up to a parachute, falling to Earth.
From what I understand, the formula for this is
...
0
votes
1answer
94 views
Rotating sphere and circular trajectory: minimum speed
I have a sphere (mass = 3 kg), constrained to a fixed length rope, rotating (radius = 5 m) on a vertical plane.
My textbook ask me about the minimum speed in the highest point in order to keep the ...
3
votes
3answers
368 views
How to measure force of impact inside container?
I am in 7th grade and for my science fair project, I need a way to measure the force on a dropped object when it hits the ground. What I am trying to determine is which packing materials provide the ...
1
vote
1answer
475 views
is gravity always the weakest force [duplicate]
Possible Duplicate:
What does it mean to say “Gravity is the weakest of the forces”?
Strongest force in nature
It is usually taught that the gravitational force is the weakest ...
0
votes
2answers
669 views
If the earth would stop spinning, what would happen?
What would happen if the earth would stop spinning? How much heavier would we be? I mean absolutely stop spinning. How much does the centrifugal force affect us?
If you give technical answers (please ...
14
votes
3answers
614 views
Why doesn't a fly fall off the wall?
Pretty simple question, but not an obvious answer at least not to me. I mean you can't just place a dead fly on the wall and expect it to stay there, he will fall off due to gravity. At first I ...
1
vote
5answers
392 views
Where does the “g” force that pilots experience come from?
I understand that it has to do with acceleration. Say a pilot does a quick maneuver and experiences a force of 5g. What exactly is happening here?
And what is this force relative to?
If someone ...
4
votes
1answer
90 views
Could this fountain, under the right conditions, technically be able to lift me up?
There is a big fountain in a lake in my city.
I was talking with a friend and we were wondering whether it would be able to lift me up. I sent a few emails and obtained information about the ...
0
votes
1answer
114 views
detect movement - how does it relate to G force
I would like to detect if a user is moving by using an android smartphone - walking or jumping doesn't matter - want to know if the user wearing the smartphone is moving.
I have found this code ...
0
votes
0answers
31 views
Gravity is a strong force or weak force? Or its not a force at all [duplicate]
Possible Duplicate:
What does it mean to say “Gravity is the weakest of the forces”?
Gravity is always a mysterious thing for me.
Sometime we say that most of stellar objects ...
3
votes
4answers
326 views
Gravitation is not force?
Einstein said that gravity can be looked at as curvature in space- time and not as a force that is acting between bodies. (Actually what Einstein said was that gravity was curvature in space-time and ...
0
votes
2answers
136 views
How do we end up with a gravity-dominant macroscopic universe from a quantum world having weakest gravity?
At quantum scale, gravity is the weakest force. Its even negligible in front of weak force, electromagnetic force, strong force.
At macroscopic scale, we see gravity everywhere. Its actually ruling ...
2
votes
1answer
308 views
Combined Gravitational Force Vectors in a Spherical Coordinate System
Asking a question here is quite intimidating for me -- while I love Physics, my high-school understanding only allows me to go so far... I've been trying to solve this problem for the last couple of ...
0
votes
2answers
287 views
When we throw an object in the presence of gravitational attraction is the mass of the object proportional to the time of fall or not?
I was confused when i saw two object of different masses (A and B)falling from the same height(h) but both of them strikes the ground at same time. Is this possible, that masses of the objects are ...
2
votes
2answers
159 views
Interaction speed between electric charges and magnetic materials
Einstein said that the speed of a matter in universe cannot exceed the speed of light.
Is it correct for electric force transmission speed from one electric charge to other one?
What is ...
0
votes
1answer
266 views
Does the earth's gravity affect horizontal movement?
In a frictionless environment, would the weight of an object affect how hard it is to move it horizontally? Since without friction, there is no horizontal force resisting your applied force, would the ...
3
votes
3answers
587 views
How does gravity force get transmitted?
How does gravity force get transmitted?
It is not transmitted by particles I guess. Because if it was, then its propagation speed would be limited by the speed of light. If it is not transmitted by ...
1
vote
4answers
396 views
Why is gravity weak at the quantum level?
Why is gravity stronger than other forces at the macroscopic level, yet weaker than other forces at the quantum level? Is there an explanation?
2
votes
2answers
2k views
All matter has a mass but does all matter have a gravitational pull?
I know that all planets and stars have a gravitational pull but does a simple much smaller object have a gravitational pull for example a pebble?
0
votes
2answers
1k views
Jumping in an elevator?
I've always been under the impression that jumping in an elevator wouldn't help at all, especially after reading a snippet of physics where Einstein said that free fall was identical to zero gravity.
...
2
votes
2answers
155 views
Raising a toolbox with a rope
Suppose you use a rope to hoist a box of tools vertically at constant speed v. The rope exerts a constant upward force of magnitude F_up on the box, and gravity exerts a constant downward force (the ...
1
vote
1answer
283 views
Calculating the force of a mass bearing down on an object
I need to calculate the force of a weight bearing down on a smaller object, constraining it from expansion.
The weight bearing down has a much bigger surface area than the smaller object.
I know the ...
3
votes
2answers
163 views
What would be the optimal weight of a ball if I want to throw it as far as possibile?
Assume the force behind my throw to be X. Assume the point of release is 2 meters above ground. Asume the ball is made of shiny steel. I'm not sure if the material matters, I'm just thinking that ...
0
votes
0answers
86 views
What would the effect of reducing inertia have on the human body, and the physics of motion [closed]
It seems to me the best theory available for the origins of inertia is that inertia arises as a radiation bath caused by the interaction of matter with virtual particle pairs an accelerating frame. It ...
3
votes
1answer
553 views
Escape velocity of a rocket standing on Ganymede (Moon of Jupiter)
I want to calculate the escape velocity of a rocket, standing on the surface of Ganymede (moon of Jupiter) and trying to leave Ganymede.
My thinking was, the kinetic energy $E_{\text{KIN}}$ must be ...
2
votes
3answers
509 views
Why do some satellites fall to Earth?
In another question How does Newtonian mechanics explain why orbiting objects do not fall to the object they are orbiting?, one can read an affirmative answer. They how do you explain satellites ...
5
votes
4answers
619 views
Alternate layman's metaphors for illustrating curved space-time
The metaphor of a surface (typically a pool table or a trampoline) distorted by a massive object is commonly used as a metaphor for illustrating gravitationally induced space-time curvature. But as ...
0
votes
1answer
107 views
Question regarding escape velocity
Haliday-Resnick-Walker state that the escape velocity will cause a projectile to move upward forever, theoretically coming to rest only at infinity.
I was wondering what the forces forcing the body ...
2
votes
1answer
470 views
How does one calculate the force applied on an object by a magnetic field?
I've tried very hard to find an answer to this question, and every path leads me to an abstract discussion of fundamental forces. Therefore, I will propose two very specific scenarios and see if they ...
0
votes
4answers
760 views
Would you feel weightless if falling or flying up in a vacuum?
Ignoring that you can't survive in a vacuum.
If you were to jump of a ledge in a vacuum (in a vertical tube eg). While falling would you feel weightless? Surely the earths gravity is still pulling ...
2
votes
2answers
253 views
Silly bet about the best way to walk up a hill
I have a silly bet with a friend of mine.
One of us argues that walking up a hill whilst leaning forward requires less exertion, due to your centre of mass being further forward, and therefore ...
3
votes
4answers
276 views
existence of other forces obeying inv square law
Is there any restriction in what we know of physics to the existence of other type of forces that obey the inverse square law in 3 dimensions.
I mean other than electromagnetic and gravitational.
...
2
votes
3answers
190 views
Making a “heavier-than-air” craft float
How big would a hollow rigid object need to be to float, (not in water but in air) if all of the air was vacuumed out and the container sealed?
0
votes
2answers
1k views
Forces in a Pendulum
Help me visualise the forces found in a pendulum. I know weight can be decomposed into $F_x$ and $F_y$.
Centripetal force, acceleration and velocity are three words that I'm confused. Centripetal ...
