Kinetic theory of gases momentum

AI Thread Summary
The discussion centers on the momentum change of a gas particle during an elastic collision with a wall. The equation for momentum change is clarified as delta px = pf - pi, leading to the expression delta px = -2mvx when considering the reversal of velocity upon impact. The second negative arises from the initial velocity being negative after the collision, indicating a change in direction. Participants confirm that understanding this concept helps clarify the momentum calculations. The explanation emphasizes the relationship between velocity direction and momentum in elastic collisions.
lukasz08
Messages
10
Reaction score
0
p=momentum=(mass*volume)

delta px = pf - pi
mvf - mvi
mvx - (-mvx) <<<<---- where does this second negative come from ? what am i missing here?
2mvx


in my book it shows that
delta px = - mvx - (mvx) = -2mvx
 
Physics news on Phys.org
When a particle bounces elastically off a wall, its velocity (and momentum) changes direction. Does that help?
 
yes i understand that so the second negative appears after the particle has hit the wall resulting in the 2mvx ?
 
ok i got it mvi = -mvf therefore -mvi - mvf = -2mvx
 

Thread '1:1 versus 2:1 Mechanical Advantage debate'

The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
View full post »

Thread 'Newton's first law?'

Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
View full post »
Thread 'Beam on an inclined plane'

Thread 'Beam on an inclined plane'

Hello! I have a question regarding a beam on an inclined plane. I was considering a beam resting on two supports attached to an inclined plane. I was almost sure that the lower support must be more loaded. My imagination about this problem is shown in the picture below. Here is how I wrote the condition of equilibrium forces: $$ \begin{cases} F_{g\parallel}=F_{t1}+F_{t2}, \\ F_{g\perp}=F_{r1}+F_{r2} \end{cases}. $$ On the other hand...
View full post »

Similar threads

Pressure exerted by a gas (derivation using the kinetic theory of gases)
Replies
9
Views
2K
Assumptions in the derivation of the kinetic theory of gases
Replies
1
Views
2K
B Colliding balls: Conservation of momentum and changes in kinetic energy?
Replies
2
Views
2K
Pressure should decrease in zero gravity?
Replies
7
Views
2K
(2/3) as constant factor In Kinetic theory of gases
Replies
7
Views
2K
Kinetic theory of gases: rebound speed and force questions
Replies
2
Views
3K
B The physics of flywheel launchers (like tennis ball shooters)
2
Replies
60
Views
4K
B Collision time interval of a gas molecule with wall of container
Replies
6
Views
2K
Why Is Time Represented as 2d/v in Kinetic Gas Theory Calculations?
Replies
3
Views
4K
Confusion about tidal locking and rotational kinetic energy
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top