Calculate KE, E, p and f for proton.

  • Thread starter Thread starter budafeet57
  • Start date Start date
  • Tags Tags
    Proton
AI Thread Summary
The discussion focuses on calculating the kinetic energy, total energy, momentum, velocity, and frequency for photons, electrons, and protons. The provided calculations yield specific values for each particle, with the proton's kinetic energy calculated as 0.0002 MeV and total energy as 938.0002 MeV. Concerns are raised about the rounding of the results, particularly the inconsistency in significant figures between the momentum and energy values. The need for verification of the proton's results is emphasized, as the calculations may not align with expected precision standards. Overall, the thread highlights the importance of consistent rounding in physics calculations.
budafeet57
Messages
23
Reaction score
0

Homework Statement


photon(0 MeV), electron(0.511MeV), photon(938 MeV) have wavelength of 2.0*10^-15 m, 2.0pm. Calculate their kinetic energy, total energy, momentum, all in MeV, and velocity and frequency.

Homework Equations


E = K + mc^2
E^2 = (pc)^2 + (mc^2)^2
E=hf
λ=h/p

The Attempt at a Solution


for photon:
K 0.621 MeV
E 0.621 MeV
p 0.621 MeV/c
v 3*10^8 m/s
f 1.5*10^20 Hz

for electron:
K 0.292 MeV
E 0.803 MeV
p 0.62 MeV/c
v 0.77 c
f 1.94*10^22 Hz

for proton:
K 0.0002 MeV
E 938.0002 MeV
p 0.62 MeV/c
v 6.6*10^-4 c = 1.98*10^5 m/s
f 2.2*10^23 Hz

I am a little bit not sure about my results regarding proton's. Any help verifying my answers will be appreciated because I don't have answer for this problem.
 
Physics news on Phys.org
You're right, but your rounding is a little weird. You have only two digits for p, but then you have 7 digits for E. With any reasonable rounding, you would have 2/3 digits for E and just get 0 for K.
 
thank you.
 
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...
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...

Similar threads

Replies
54
Views
10K
Replies
2
Views
1K
Replies
6
Views
2K
Replies
8
Views
2K
Replies
3
Views
4K
Replies
10
Views
4K
Replies
1
Views
2K
Back
Top