# Recent content by Rick88

1. ### Rocket Height

From the moment the fuel finishes, only one force acts upon the rocket: gravity. So find the the velocity the rocket possesses after those 7 seconds of propulsion and then use the constant acceleration formulae to find the height at which the rocket has v=0. R.
2. ### A man in an elevator at the forces affecting him

Just use Newton's Laws to know that a force corresponds to an acceleration. As the elevator moves, a new force is exerted on the man. The direction of this force depends on the direction of motion of the elevator. Does it make sense?
3. ### Need help. How do i start the problem, thank you.

The latent heat is the amount of energy absorbed or emitted by a system during a phase transition (liquid -> solid, say) carried out at constant temperature. You should proceed in calculating what the latent heat is in this instance; then it should be fairly obvious what to do ;) R.
4. ### Density Parameters using Mathematica

I'm supposed to solve for re for different values of the omegas. so say 0.2, 0.8; 0.5, 0.5 and so on. And the omegas are constant.
5. ### Density Parameters using Mathematica

Ok, thanks for your suggestion. Right, I need to solve equations (1) and (3) for two omegas only. That is, two of the omegas would be zero, whilst the other non-zero. And the sum of the omegas must always be 1. What I've written so far in Mathematica is: sol = NSolve[r2[z] ==...
6. ### Density Parameters using Mathematica

Homework Statement hello, I have to solve a couple of equations on Mathematica for a project, and since they are not really working out, I wondered if you could help me out a bit. I need to solve equation (1) (you can find the equations in the .doc attached) and plot the solution for a...
7. ### Probability of neutrino-electron scattering

Yeah, that's what I thought, but I am confused about how to find the total probability. An integral or what?
8. ### Probability of neutrino-electron scattering

Homework Statement Ok, I'm given a formula for the cross section of the scattering and I've been told that the detector is a column of water of depth 10m. I need to find the probability of the scattering within the detector. Homework Equations σ = E(in MeV) x 1.5x10-44 cm2 The...
9. ### Integrating an equation with scale factor

Homework Statement Ok, the problem is simple enough, I think. I just think I'm missing something obvious. I have an equation involving the scale factor R(t) and need to integrate it. I am at the first equation and need to get to the second by integrating (with respect of R, I suppose)...
10. ### Constructive or destructive interference- Car radio

Use c=νλ with the values given for the frequency and the speed of light. (ν here is the greek letter "nu", denoting frequency) From this, you'll find the wavelength of the wave. Now, the waves will "hit" the wall and be reflected towards the car again, so the intereference will be costrunctive...
11. ### Angular velocity of an airplane propeller

yes, it is right. Just maybe don't leave it as 3800pi/60, but compute the actual value. (But i'm sure you were going to do it anyway)
12. ### Capacitors in Series

Because there are two capacitors in the circuit. If you use C=C2 (1e-6), then you are just considering a circuit having *one* capacitor. You basically need to find C to see how the capacitance is split between the two capacitors. That would also give you how the charge is split.
13. ### Rocket Calculations

Just use: p=mv and a=dv/dt (and F=ma, of course).
14. ### Doppler Shift Light from another galaxy

Bave you tried: and ?
15. ### Find magnitude, help

It is indeed.