Relativistic Addition of Proton Velocities

AI Thread Summary
An electron moves at 0.90c to the right, while a proton moves at 0.70c to the left relative to the electron. To find the proton's speed relative to the laboratory frame, the correct relativistic velocity addition formula should be used. The initial formula provided was incorrect, prompting a search for the proper equation. The discussion clarifies that the lab frame should be treated as the moving frame and the proton's frame as stationary. The confusion was resolved by confirming the correct application of the relativistic velocity addition formula.
catch-22
Messages
5
Reaction score
0

Homework Statement



An electron moves to the right with a speed of 0.90c relative to the laboratory frame. A proton moves to the left with a speed of 0.70c relative to the electron. Find the speed of the proton relative to the laboratory frame.

Homework Equations



Vx'=[Vx-V]/[1+(v2/c2)*Vx]

The Attempt at a Solution



I have no idea where to start other than substituting 0.9c in for V.
 
Last edited:
Physics news on Phys.org
Using the Lorentz transformation for velocity is a perfectly fine approach. But that formula isn't correct. (Not even dimensionally.) So look up the correct formula.

Hint: Let the lab frame be the moving frame (primed) and let the proton's frame be the "stationary" frame (unprimed).

You can also just use the "addition of velocity" formula, which is derived from the Lorentz transformation (of course).
 
Ahh, got it. Our physics teacher gave us a slightly off formula, so it was cleared up today. Thanks!
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Basic special relativity addition of velocities problem
Replies
4
Views
7K
Find the Speed of an Electron in the lab frame
Replies
8
Views
3K
Speed of an object relative to another
Replies
1
Views
2K
Compute relativistic addition of velocities
Replies
1
Views
1K
Kinetic Energy of Colliding Protons
2
Replies
54
Views
10K
Magnetic Field Force of a proton
Replies
6
Views
2K
What Was the Initial Speed of the Proton in a Collision?
Replies
2
Views
3K
Relativistic mass/length contraction problem
Replies
3
Views
2K
Velocity and Acceleration Relationship
Replies
13
Views
2K
Lambda decay, momentum of the pion and proton
Replies
33
Views
4K

Hot Threads

Recent Insights

Back
Top