All Questions
24
questions
1
vote
3
answers
132
views
Pressure due to a single photon
I'm interested in the pressure exerted on a material when a single photon is absorbed.
I have written the following expression for pressure:
$$
P = \frac{hf}{cA\Delta t},
$$
where $A$ is the area over ...
- 13
0
votes
1
answer
112
views
Mass + velocity to pressure. How to measure pickleball flex without hurling it?
I want to know how much a pickleball (it's like a whiffleball) compresses when it hits the floor. I can't afford a 500,000 fps camera, so maybe an approach using basic principles would work. I also ...
- 103
5
votes
5
answers
1k
views
How do we explain the motion of a time-reversed emptying balloon in vacuum?
Imagine a balloon filled with air, let loose in outer space. There is an imbalance of pressure pushing to the insides of the balloon, and this imbalance is the motor of motion. There is no pressure in ...
0
votes
1
answer
155
views
Question About Momentum Flux Analysis Using Force Equations In Fluid Mechanics
I was just revising fluid mechanics "Momentum Flux Analysis & Control Volumes" and I just noticed that there is an assumption in which we can assume to deal with gauge pressure instead ...
- 113
0
votes
1
answer
87
views
Is it possible to compress gas without making it hotter?
First of all, this is just a purely theoretical thought experiment:
Let us consider another situation. Suppose that the piston moves
inward, so that the atoms are slowly compressed into a smaller ...
- 211
0
votes
3
answers
422
views
Why water coming out from narrow pipe hurt more than same amount of water coming out from broad pipe with same flow rate?
If you take a narrow and a broad pipe and make same amount of water pass through I.e same flow rate .
And stand at front of both of them
Water from Narrow one hurts more!
Why although same amount ...
0
votes
1
answer
63
views
Question about force of a blow from a wide flat surface
Sometimes, when we surf the internet we always see something like bears, lions, tigers, etc. have bone-breaking paw swipes. While we know the weight of the animal and the speed play the role whether ...
- 364
1
vote
0
answers
32
views
Dynamics of a football
Why can toe kick cause greater change in the ball's momentum than kicking with the whole instep in contact with the ball? Perhaps it has something to do with how the foot's momentum is transferred in ...
- 97
3
votes
3
answers
1k
views
The force exerted by a single molecule
In the chapter of the kinetic theory of gases in a basics undergraduate physics book, it says the force exerted by a single molecule on a wall is calculated as $F = \frac{\Delta p}{\Delta t} = \frac{...
- 157
2
votes
2
answers
2k
views
Why is the relation between coefficient of restitution and air pressure of a basketball logarithmic?
Perhaps this is due to the spherical shape of the ball but yea, i've conducted the experiment for school and i'm trying to work through justifying this but need assistance.
edit: here's the data
- 159
1
vote
0
answers
29
views
Derive equation for theoretical pressure rise in tunnel from jet fan?
This is the rough setup i'm referring to
I believe this is the final equation for the maximum theoretical achievable pressure rise in the tunnel due to a running jet fan :
See Full paper ...
- 135
1
vote
1
answer
319
views
Fluid pressure in Neumann's triangle for triple junctions
Consider a point of contact where three fluid phases meet. The Neumann's triangle rule for this case is usually written as,
\begin{equation}
\frac{\sigma_{\alpha\beta}}{\sin \gamma} = \frac{\sigma_{\...
- 211
0
votes
1
answer
690
views
Is it momentum/force or pressure that determines the damage of an impact?
So a tiny object and a huge object that have the same mass and velocity strike a surface. Because they have the same mass and velocity, they would have the same momentum and will deliver the same ...
- 1
1
vote
0
answers
711
views
Is static pressure the pressure used in the navier-stokes equations?
I believe in the image below, the pressure (P) being quoted is the same type of pressure that is used in the navier-stokes equations. Is this pressure the static pressure of the fluid?
i.e. if i were ...
- 135
3
votes
2
answers
591
views
Is it right to consider an average force over time rather than an impulse?
In a proof of the pressure exerted on a surface by a gas, the average force exerted by a particle on the surface $$ \vec{F} = \frac{\Delta \vec{p}}{\Delta t}$$
is used, where $\Delta t$ is the time ...
- 71