Recent content by snellslaw

Hi HallsofIvy! like say you insert some data points and then use your calculator to calculate the linear regression. the calculator spits out y=0.0283x+0.0012, r2=0.998 so the r2 is the coefficient of determination

A text says that if you calculate the linear regression of data points and you get the equation y=mx+b with an r2 value, the error in the slope is given by: δm/m=2(1-r) No explanation was given. Could someone please explain this formula? Thanks!

@mps: hey are you preparing for the same thing? :P Thanks everyone!

Thanks TinyTim! So is "a" the spring constant?

Attached is the formula for the equation of motion for a system of coupled oscillators. Could someone please tell me what the variables and indices refer to here? Thanks! :)

Thanks tiny-tim! :D I think the line you quoted was not my question however; we need vi2cos2(θ)/2g = gR2/2vi2 but this leads to cos2(θ) = sin2(2θ) which is not an equality. Thanks again!

Thanks! could you please explain further how you know this to be true? If you look here: http://en.wikipedia.org/wiki/Trajectory#Range_and_height I'm assuming x is the max range R? Then y = vi2sin2(θ)/2g = vi2/2g * (1 - cos2(θ)) Now if this were to match the equation in OP, then we need...

Where did this equation come from? (attached) I can only think of the equation for d found at the end of the section in this wikipedia article: http://en.wikipedia.org/wiki/Range_of_a_projectile#Flat_ground Thanks!

OHHH thanks! :D

I get how to go from 5 to 6 (set cosα=0) but how do you get 7? Thanks!

Thanks but I don't know how to proceed. Could you please help me out?

By length contraction, ship A thinks B is a distance 2.52x10^12/√(1-0.8^2) away thus the time is 2.52x10^12/√(1-0.8^2) / (0.946c) = 14799... still not right :(

By the way, I know how to solve this problem by first calculating the time of collision as seen from the Earth. I just want to know how to calculate it using distances and speeds from the point of view of the rockets as well.

Thanks! How would I calculate the distance in the rocket's rest frame (for each rocket)?

Hello physics forums people, could you please help me? Homework Statement According to an Earth observer, rocket 1 has speed 0.800c, rocket 2 has speed 0.600 c and rockets are initially 2.52x10^12 m apart. The rockets are approaching each other. According to each Rocket, how long is it...