# Search results

1. ### Double slit experiment with a glass-covered slit of unknown n

So for the first bit you're saying that the thickness of the mirror is equal to 5 times the wavelength of the light?
2. ### Double slit experiment with a glass-covered slit of unknown n

Homework Statement A double-slit experiment uses a helium-neon laser with a wavelength of 633 nm and a slit separation of 12mm. When a thin sheet of glass is placed in front of one of the slits, the interference pattern shifts by 5 fringes. When the experiment is repeated under water, the shift...
3. ### Partial Differential Equation in Special Relativity

Is it simply due to the fact that ##u_{xx}-c^2u_{tt} \neq u_{x'x'}-c^2u_{t't'} ##, so that if ##u## satisfies the wave equation in ##x##,##t## coordinates, then it does not satisfy the same equation in the ##x'##,##t'## coordinates? Or do I deduce it mathematically?
4. ### Partial Differential Equation in Special Relativity

I give up. Can you guide me through this. Please. Thanks
5. ### Partial Differential Equation in Special Relativity

Can you give a little bit more hints than that please? Thanks
6. ### Partial Differential Equation in Special Relativity

Homework Statement (a) Light waves satisfy the wave equation ##u_{tt}-c^2u_{xx}## where ##c## is the speed of light. Consider change of coordinates $$x'=x-Vt$$ $$t'=t$$ where V is a constant. Use the chain rule to show that ##u_x=u_{x'}## and ##u_{tt}=-Vu_{x'}+u_{t'}## Find ##u_{xx},u_{tt},##...
7. ### Reflection and Transmission of acoustic waves at a boundary

Oh so what you mean is that it doesn't matter what I set the incident amplitude as, because at the end i'm going to get a percentage/ratio of it? Kinda like how for probability it all adds up to 1?
8. ### Reflection and Transmission of acoustic waves at a boundary

Does it have something to do with ratio? To me it's quite vague
9. ### Reflection and Transmission of acoustic waves at a boundary

Homework Statement An interface is formed between a block of aluminium (density = ##2.70 \times 10^3 kg/m^3##, speed of sound =##6.40 \times 10^3m/s##) and a block of copper (density = ##8.96 \times 10^3 kg/m^3##, speed of sound =##4.76 \times 10^3m/s##). Longitudinal waves travelling through...
10. ### Change of variables in Heat Equation (and Fourier Series)

From the given BCs for ##u##, am I right in saying that BCs for ##v## is ##v(0,t)=v(a,t)=u(0,t)+C=2C##? Also by substituting ##u(x,t)=v(x,t)+C## into the PDE do you mean partially differentiate it then substitute in like $$v=u+C$$ ...
11. ### Change of variables in Heat Equation (and Fourier Series)

Q: Suppose ##u(x,t)## satisfies the heat equation for ##0<x<a## with the usual initial condition ##u(x,0)=f(x)##, and the temperature given to be a non-zero constant C on the surfaces ##x=0## and ##x=a##. We have BCs ##u(0,t) = u(a,t) = C.## Our standard method for finding u doesn't work here...
12. ### Rotational kinematics of a spherical rock upon collision

Thanks guys I appreciate this alot. :)
13. ### Rotational kinematics of a spherical rock upon collision

Then the distance to the centre of mass of the big is constantly changing as the small rock approaches the CoM?
14. ### Rotational kinematics of a spherical rock upon collision

So the angular momentum L = mvr which taking r as a=0.5, gives a result of L=50 which is apparently the right answer. But why would r be a if its rotating about point O?
15. ### Rotational kinematics of a spherical rock upon collision

So the angular momentum of the small rock about point O before the collision is its mass m * distance from point O * its angular velcoity about point O. But the angular velocity is constantly changing?
16. ### Rotational kinematics of a spherical rock upon collision

I understood that when in part a) there's no rotation because a = 0. I noted that my question is Qd) which asked for the angular velocity and angular momentum when a = 0.5, so surely there's rotation?
17. ### Rotational kinematics of a spherical rock upon collision

I don't see how you could calculate the angular momentum of the small rock before the collision since L=Iw= (2/5)(MR^2)*(v/R) = (2/5)(MRv)=(2/5)(1)(1)(100)=40??
18. ### Rotational kinematics of a spherical rock upon collision

So I get it now that the v in v=rw applies to tangential velocity and you're saying that the velocity obtained after conservation of momentum is the linear velocity of the rock as a whole so it v =rw wouldn't apply? What is the relationship between linear velocity and tangential velocity?Or does...
19. ### Rotational kinematics of a spherical rock upon collision

So the linear velocity after the conservation of momentum came out to be 0.01m/s. Using w = v/R where R is the radius of the big rock after collision, w = 0.01/1 = 0.01rad/s. L = Iw = (2/5) MR^2 * w = ((2/5)*(10000kg)*(1m)^2)*0.01m/s = 40kgm^2/s. However the answer comes out to be 50kgm^2/s and...
20. ### Rotational kinematics of a spherical rock upon collision

Homework Statement A small spherical rock of mass collides in space with a large spherical rock of mass as indicated in the diagram. After the collision the rocks stick together to form a single spherical object. https://postimg.org/image/fltmg3bj5/ (New here so I've no clue how to upload...