Calculate the charge density in a certain region, in the following two cases:
the electric field in spherical coordinates is given by:
e(r)=ar^2 r+bcosθ/r θ+cϕ
where a, b and c are constants
the electric field in cylindrical coordinates is given by:
er=a/rr+br θ+cr^2z^2z
where a, b and c are constants

You have been hired to design a spring-launched roller coaster thatwill carry two passengers per car. the car goes up a 10-m highhill, then descends 15m to the track's lowest point. you'vedetermined that the spring can be compressed a maximum o 2.0m andthat a loaded car will have a maximum mass of 400kg. for safetyreasons, the spring constant should be 10% larger than the minimumneeded for the car to just make it over the top. a) what spring constant (k) should you specify ? b) what is the maximum speed of a 350 kg car if the spring iscompressed the full amount.