All Questions
Tagged with newtonian-gravity free-body-diagram
18
questions
52
votes
3
answers
21k
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If Newton's third law is true, why can we sink in sand? [duplicate]
Newton's third law of motion states that every action has an equal and opposite reaction. That is the reason we do not sink into the earth, because when our weight exerts a force on the earth it also ...
15
votes
7
answers
30k
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Is gravity a force and if so what is its opposite?
For every force there is an equal force in the opposite direction on another body, correct?
So when the Suns gravity acts on Earth where is the opposite and equal force?
I also have the same ...
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12
votes
5
answers
36k
views
Why can't a rope be pulled completely straight?
I have found several discussions on how to calculate the sag of rope that is tied off at two points (like a tightrope), and I understand it to a certain extent. What I can't wrap my head around is how ...
- 225
13
votes
3
answers
2k
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How does the center of gravity work?
In free body diagrams, such as a beam attached horizontally to a wall, $F_g$ is always shown acting on the center of gravity of an object.
My question - is this the case in real life, where gravity ...
5
votes
4
answers
5k
views
What Keeps a Pendulum Moving In a Circular Path?
From the figure, we know that $F_{net} = mg\sin\theta$. Now, this force $\vec{F_{net}}$ is in the direction of the velocity $\vec{v}$ of the bob, both are tangent to the path. Therefore, the net ...
- 191
3
votes
6
answers
106k
views
Forces on a ball thrown upwards
When a ball is thrown up in upward direction, it is said that force is in downward direction. Why we don't we consider the force given to the ball to throw up in the upward direction? Is there is no ...
2
votes
3
answers
3k
views
What is the force pair for the normal force? Clarification on Newton's 3rd Law
In the process of trying to wrap my head around Newton's 3rd law I've come across 2 definitive statements.
Forces must occur in pairs
Forces must act on different bodies
This is confusing to me when ...
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0
votes
1
answer
8k
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Does Newton's 3rd law of motion apply when a person is standing still on a ground?
When a person is standing still, the action of the Earth on their body is a gravitational force. What is the reaction force? Is it the person's weight acting on the Earth?
45
votes
7
answers
21k
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Hanging a hammer from a table and a stick so that its midpoint is outside of the support of the table
I came across this pic on the internet today. At beginning I thought it is just not possible because the centre of mass is way off so gravity will generate torque making the stick and hammer fall. ...
- 626
11
votes
1
answer
1k
views
Earth as a perfect sphere and an object trying to stand still
I have imagined the Earth as a perfect sphere with uniform mass density and I put an object somewhere between the equator and the north pole at rest with respect to earth. And also in my imaginary ...
- 1,502
2
votes
3
answers
198
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Problem with gravity
Sorry if this question is dumb, but I don't seem to have a grasp on it.
Suppose you are on a rock in space, with no external forces acting. The rock attracts you with a force given by
$$F=G\frac{...
1
vote
5
answers
354
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Reduced-gravity flight (A300 0-G): what is actually reduced?
I doubt I can hide from the effects of gravity when I'm close to Earth. We usually don't question this biker is fully experimenting gravity:
Source.
But with the well-known "reduced gravity" ...
- 183
1
vote
4
answers
957
views
Zero gravity - how it is possible?
If planets in the solar system are under the influence of gravity, how does one achieve zero gravity just outside Earth? (Please correct the question if the terms are wrong, but I hope the question is ...
- 257
0
votes
2
answers
91
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Where do we use the maximum? [closed]
In the above problem,we have been asked to find the maximum value of $\frac{M}{m}$. But the solution the book ended up giving is the normal balancing of forces in free body diagram and came up with ...
- 1,179
-1
votes
2
answers
171
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Is it possible for a particle to slide on a frictionless sphere and orbit the sphere? [closed]
We are in an isolated system consisting of a large massive smooth sphere/planetoid with radius $R$ and due to its mass an nearly constant acceleration $g$ exists in its vicinity.
A small particle is ...
- 1,270