Asolid ball mass=1kg and radius=.10m rolls down a ramp(with friction) and goes through the loop.
a) what is “h” if the ball is on the verge of leaving the track when ut reaches the top of the loop?
b) what is ‘h’ if the ball on the verge of leaving the track when it reaches the top of the loop is hollow?

Why is there friction between objects

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

Consider a hydrogen atom in the ground state. what is the energy of its electron? =e= jj now consider an excited‑state hydrogen atom. what is the energy of the electron in the =5n=5 level? =e5= j