All Questions
25
questions
-1
votes
2
answers
116
views
How Fast Must a Man Run to See Rain Falling horizontally?
The fact that tan 90° is undefined indicates a key issue in the problem.
Does this mean it is impossible to observe rain falling at 90 degree?
When rain is observed to be falling at 90° with the y-...
-2
votes
1
answer
61
views
The distance problem [closed]
Say a car has to move from Point A to Point B on the surface of the earth. The car starts from rest at Point A at time $t=0s$ reaches point B at time $t=10s$ with a constant velocity of $1000 m/s$. ...
- 87
0
votes
1
answer
121
views
Velocity of Separation and Relative Velocity
I have some problems in understanding a concept, which has been used in the problem in the picture:
I don't understand what are we actually using to solve this question. Are we using relative ...
4
votes
5
answers
711
views
Can't understand a statement about motion
From the book where I am studying motion, It says
Motion is a combined property of the object under study and the observer. There is no meaning of rest or motion without the viewer.
I know that, for ...
- 157
5
votes
5
answers
1k
views
How is a change in KE the same in every inertial reference frame?
This is not about special relativity, so assume speeds are much less than $c$.
This article says a change in kinetic energy (KE) remains constant in all inertial reference frames.
So the kinetic ...
- 410
0
votes
1
answer
48
views
Kinetic energy consistency
Suppose a vehicle 1 is on the top of another vehicle 2 (we can think of it like a big platform).
Imagine the following independent experiments:
Suppose that the top vehicle accelerates to a speed $...
- 31
0
votes
3
answers
239
views
A question about relative motion and how to make sense of it
So, here is the question:
Assuming the 2D Cartesian system and the basis vectors $\hat{i}$ and $\hat{j}$, we have two cars A and B located at (0,6) and (-30,0) respectively. Car A starts moving with a ...
- 169
4
votes
3
answers
1k
views
Kinetic energy "paradox" -- where am I wrong here? [duplicate]
Body $A$ is at rest and has mass $2$, so the energy required in order to accelerate it to a speed of $v$ is $v^2$, and so the energy required in order to accelerate it to a speed of $2$ is $4$.
On the ...
- 143
0
votes
1
answer
107
views
CoM-and-relative velocity
In our scrip we are considering the elastic collision between two particles, one with inital velocity $\vec v$ and the other $\vec w$. We also consider that the particles have the same mass.
...
- 1,398
1
vote
1
answer
124
views
Velocity of an object with respect to the same object
I know that velocity of an object with respect to the same object is a null vector but I'm not able to get a grasp of it.
Whatever I had thought till now is that if I'm sitting in a train (which may ...
- 882
2
votes
2
answers
131
views
Can I apply Newton's equations of motion to relative motion?
We know that
Velocity of A relative to B is
$$ \vec v_{A|B} = \vec v_A - \vec v_B $$
and Acceleration of A relative to B is
$$ \vec a_{A|B} = \vec a_A - \vec a_B $$
So, is it correct to do this to ...
- 227
0
votes
2
answers
296
views
Why is relative motion at constant velocity the same as being at rest?
If I am a passenger who plays catching-the-ball game inside a vehicle that moves with a constant velocity in a straight road, why can I catch the ball repeatedly that as if the vehicle is at rest? How ...
user282164
1
vote
4
answers
138
views
Motion between two particles in a relative manner
Suppose a particle A is travelling in east direction with velocity of x m/s and another particle B is travelling with velocity y m/s in the west direction. Why does the the particle B appears to move ...
0
votes
1
answer
117
views
Relative motion between two particles
I already know the relation of relative velocity as :
Vab=Va-Vb
So is there any derivation for this relation or is just how it is defined?
Relating to this i am finding some hard time to imagine why ...
1
vote
3
answers
250
views
Defining what it means for a reference frame to move with a velocity $\mathbf{u}$ with respect to another
In describing a Galilean transformation, for example, one might say that if a reference frame $S'$ is moving at a velocity $\mathbf{u}$ with respect to $S$, then an object traveling at a velocity $\...
user113773