Tagged Questions
2
votes
2answers
160 views
Foucault pendulum
The equations of motions for a Foucault pendulum are given by:
$$\ddot{x} = 2\omega \sin\lambda \dot{y} - \frac{g}{L}x,$$
$$\ddot{y} = -2\omega \sin\lambda \dot{x} - \frac{g}{L}y.$$
What are the ...
2
votes
2answers
74 views
Reality error and relative velocity
Suppose a person is walking in rain carrying an umbrella. He is tilting his umbrella at some angle with the vertical so as to protect himself from the rain. But a neutral observer who is standing ...
2
votes
2answers
151 views
Fictitious forces confusion
I have a hard time understanding the subject of fictitious forces. Let's discuss a few examples:
1) I'm sitting inside a vehicle which is accelerating in a straight line. I feel like someone is ...
3
votes
2answers
167 views
Second law of Newton for variable mass systems
Frequently I see the expression
$$F = \frac{dp}{dt} = \frac{d}{dt}(mv) = \frac{dm}{dt}v + ma,$$
which can be applied to variable mass systems.
But I'm wondering if this derivation is correct, ...
0
votes
2answers
94 views
Really basic mechanics and Galilean Relativity question
Consider two solid objects: A and B.
System 1:
A <----- B
10m/s
System 2:
A -----> B
10m/s
...
2
votes
3answers
307 views
The two faces of $F = m*a$
As I have understood,
$F(t)=m \cdot a(t)$
can have 2 different meanings:
When applying an external force $F$ on a point mass of mass $m$, the resulting acceleration of that mass at time $t$ is ...
1
vote
2answers
525 views
Flying a toy helicopter inside an accelerating train
Scenario:
You ride in a train, you have this helicopter toy. The train is not yet running when you flew your helicopter on a constant altitude (say 1 meter above the train's floor).
Question:
What ...
1
vote
1answer
470 views
Earth as approximate inertial frame of reference
In many practical applications one can consider the earth approximately as inertial reference system (though it is non inertial).
Is there any quotable reference, where this claim is supported by a ...
3
votes
6answers
1k views
Is there any true inertial reference frame in the universe?
Is there any true inertial reference frame in the universe?
Newton's first law states that an object at rest remains at rest, and an object performing uniform motion performs uniform motion, until ...
1
vote
3answers
705 views
Inertial frames of reference
I'm struggling with the notion of an inertial frame of reference. I suspect my difficulty lies with the difference between Newtonian and relativistic inertial frames, but I can't see it.
I've read ...
5
votes
11answers
2k views
Why do we say that the earth moves around the sun?
In history we are taught that the Catholic Church was wrong, because the Sun does not move around the Earth, instead the Earth moves around the Sun.
But then in physics we learn that movement is ...
