M

I have a few bruises on the front my shins from bumping into stuff that have been there for years. I remember exactly when I got them, but they never went away. They don't hurt and if I bruise anywhere else on my body, it heals completely normally. This has only been happening for the past few years and the only thing I might possibly be able to attribute it to would be a change in birth control.

Any ideas?

The average lifetime of a pi meson in its own frame of reference (i.e., the proper lifetime) is 2.6 x 10^-8 s. It moves at a speed of 0.95c and I found the lifetime from an Earth observer to be 8.33x10^-8.

The next question asks for the distance it travels before decaying, as measured by an observer on Earth. I got 24.97 and my online homework says I'm within 10% of the correct value but I don't know what I need to do to get the completely correct answer.

The third part confuses me completely because I don't have part 2, even though I have a hunch that it's the easiest part. It asks how far it would travel if time dilation did not occur.

Help! Thanks!

Three discrete spectral lines occur at angles of 10.2°, 13.6°, and 14.8°, respectively, in the first-order spectrum of a diffraction grating spectrometer.

(a) If the grating has 3720 slits/cm, what are the wavelengths of the light?

I got 542 nm for the first angle, and 703 for the second but my homework website is saying that I'm wrong. I did some problems that had different numbers and I got it right, so I don't know if I'm typing my numbers wrong or something but I am just not getting the right answer. Can somebody verify before I ask my teacher if the answers are correct? Thanks!

A ray of light strikes a flat 2.00 cm thick block of flint glass (n = 1.66) at an angle of θ = 27.0° with the normal. Trace the light beam through the flint glass and find the angles of incidence and refraction at each surface.

The question wants the angles of refraction at both the first and second surface, which I had no problem finding, but it also wants the angle of incidence at the second surface, as it's coming out of the slab. I have a feeling the solution is probably totally obvious, but I'm just not seeing it!

I have three wavelengths, 400 nm, 500 nm, and 650 nm. I need to prove that the angles of refraction vary with wavelength when they go from air through a block of crown glass.

What I tried doing was solving for a relative incidence of refraction for each wavelength by taking n=589/400, etc. and then plugging that into Snell's Law for each but I'm still not getting the right answer.

Am I on the right track?

At 20°C the carbon resistor in an electric circuit connected to a 4.0 V battery has a resistance of 154 ohms. What is the current in the circuit when the temperature of the carbon rises to 86°C?

I don't know what step I'm missing... I'm confused!

A point charge of 4.00 x 10^-9 C is located at the origin. How much work is required to bring a positive charge of 1.00 X 10^-9 C from infinity to the location x = 30.0 cm?

I never know how to get started with this graphical stuff!!

IMDB said that powdered milk was supposed to be used as a stand-in for real cocaine but apparently it was not. So what can be substituted? And how much does that really blow (pun slightly intentional) to snort something like powdered milk or cornstarch?

How did the relationship between Mr. Thornton and Mr. Higgins change during the last 100 pages or so (Vol II: ch XV-XXVII)? How did Margaret's lingering presence affect their relationship?

It happens when you're driving on the freeway and there is only one rear window partially rolled down but it stops when another one is cracked. I'm guessing it has to do with pressure since it happanes in many four-door cars I've been in, but I'd like a more specific answer please.