fairylight

What are the main flaws of the Bohr atom? does anyone know a good website that would explain them???? thanx

To astronauts pass each other at a relative speed 0.8c. At the instant their spaceships pass they sychronize their clocks and when A reads 10mins, a flash of light will be sent to B. According to B what does clock A read when the flash is sent, and what does B read when A sends the signal? For the first part i used root [1- (v/c)^2] and found the time on A to be 1000seconds. Im confused about how to work out the second half of the question. If the speed of A is relative to B then surely the time on B would be 10mins?? But that seems wrong to me! help!!!! thanx!

how do i work out Zeff in He if i have the first ionization energy - 2372kJ/mol and the ionization energy for He+ - 5250kJ/mol. i know that IE is proportional to Zeff squared, but surely i cant work out the actual value for Zeff with only this information???? im really confused!

Why are all the values of electron affinity positive except for the group 2 elements and N?

How does F=GMm/r2 predict Keplers Law T^2 is proportional to R^3? I cant see how to prove it! please help!

so wud i find the time it takes for the stone to reach its peak...using the equations of motion then just double for time to reach the ground? is it v=u+at ??????

so do i just do change in velocity / acceleration to get time?! like 20/9.81. surely theres more to it than that????!!!! lol im awful at physics!

What was Newton's Universal Law of Gravitation? i have to write an essay on it and im not actually a physics student! so was wondering if anyone could give me a few pointers? thanx xx:embarass:

I have a projectiles problem, ive been puzzling for hours and just cant seem to work it out! Its probably so simple but if someone could point me in the right direction please help! A stone is hurled into the air on level ground with a horizontal component of velocity 30m/s and a vertical component of 20m/s. How long before the stone falls to the ground? Do i have to find the resultant velocity, then the height before i can work it our or do i just use acceleration due to gravity? Im so confused!!! :confused:

Hi im preparing for uni interviews to do Chemistry and i was wondering if anyone could give me some examples of oscillatory reactions and their mechanisms. Thanx so much fairylight x

OK im prob being really stupid, but i cant for the life of me work out how to do this problem. can someone help??? A random variable X takes the integer value x with probability P(X=x) defined by P(X=x) = kx^2, x = 1, 2, 3 P(X=x) = k(7-x)^2 x = 4,5,6 P(X=x) = 0 otherwise Find the value of k

Its a basic MChem 4yr FT course. the fourth year is a year in industry. I have the grades i need, its just anything u can suggest to read, or look at for reference!!!!

Heya im 17 and about to start thinkin bout Uni interviews. I wanna do chemistry at oxford. ne tips of ne books or research i shud do before i plan it out???? thanx

I find them confusing too. It takes me ages to work them out!