These equations are rather useful, but I just want to know if Pafter = (E', p', 0, 0). If so I can substitute E' as E+m and p' as p, using conservation of energy and momentum laws. Thanks to the third equation you've given me, I can say that p = √(E2-m2) and p' = √(E2-m2) and solve for m' since...
Homework Statement
A photon with energy E collides with stationary mass m. They form a single particle together, what is this new particle's mass and what is its speed?
Homework Equations
Energy-momentum 4-vector P=(E, px, py, pz)
Possibly P2=m2
The Attempt at a Solution
Using 4- momenta, the...
If you had twin 1 on the earth, and twin 2 fly to a star and back at a speed of v with the Earth and star separated by a distance L, twin 1 sends out flashes at intervals of t seconds (measured in his frame). Taking into consideration the numbers of redshifted and blueshifted flashes that the...
Homework Statement
Two trains of proper length L move toward each other in opposite directions on parallel tracks. They both move at speed v with respect to the ground. Both trains have clocks at the front and back, and these clocks are synchronized as usual in the frame of the train they are...
ml^2 = I? Multiplied by 2 since the inertia for one of the bars is the same as the other?
How on Earth do I solve this differential equation for period T?
I always have issues with the moment of inertia. But okay the expression should look like: d2θ/dt2*I = -kθ and I should rearrange everything to find dt which happens to be the period?
I don't quite understand the inertia but perhaps it is the sum of the contributions from the two masses? So m =...
x = 0.5, that's the distance between the two m's. Okay, but is that the right equation for two-point masses? I = (m2/2m)x^2 since m and M are the same?
α = d2θ/dt2 something like that?
I'm not sure if this is correct, but could I relate spring constant to torque? τ=-kθ
And I realize now that ml^2 isn't the inertia for two-point masses? That should be: I = (mM/m+M)x^2
If I relate it to τ= Iα then: -kθ = Iα
Hmmm, can I say that α = ω/t where t is the period and just try to find...
Okay! That's what I was thinking, I just needed some confirmation just to be super safe. And finally got the right answer! Thank you so much for your help! You and ehild. :smile:
Hmmmm, okay!
So here are the variables I currently have:
d (length of rod) = 1.4m
r = 0.2m
m = 3.9kg
I = 1/3 m d2+ ( 1/2 mr2 + md2 ) = 10.27kg*m2
T = 2π√(I/MgL)
M (combined mass) = 7.8kg
I = 10.27kg*m2
g = 9.81m/s2
L = Wait how do I get this using the centre mass of 1.05m?