A boy on a swing set has a speed of 4.5 m/s and a centripetal acceleration of 8.1 m/s2 at the bottom of his swing. How long are the ropes of the swing? Pls help

Two polarizers are oriented at 70∘∘ to one another. unpolarized light falls on them. what fraction of the light intensity is transmitted?

The magnitude of the poynting vector of a planar electromagnetic wave has an average value of 0.939 w/m^2 . the wave is incident upon a rectangular area, 1.5 m by 2.0 m, at right angles. how much total electromagnetic energy falls on the area during 1.0 minute?

Select the correct answer. what does the process of natural selection involve?