The atomic number of uranium-235 is 92, its half-life is 704 million years and the radioactive decay of l kg of 235u releases 6.7x10^13 j. generally, radioactive material is considered safe after 10 half-lives.

assume that a nuclear powerplant can convert energy from 235u into electricity with an efficiency of 35%, the electrical transmission lines operate at 90% efficiency, and flourescent lights operate at 22% efficiency.
1.) what is the overall efficiency of converting the energy of 235u into flourescent light?
2.) how much energy from 1 kg of 235u is converted into flourescent light?

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 710 n/m. it is initially at rest on an inclined plane that is at an angle of θ = 23° with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is μk = 0.19. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. a) what is the block's initial mechanical energy? b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.

What’s #16 asking and how do i solve it?

Observations show that interstellar clouds can have almost any shape and