You are helping to design a new fire escape for your third-floor apartment. You step out the window onto a crossbar that is attached to a rope, which in turn is wound around a massive solid cylindrical flywheel that can turn on its axis.
As you fall at increasing speed, the rope causes the flywheel to turn at increasing angular velocity. Your task is to
choose a flywheel that will enable you to move at a safe 2.0 m/s when you reach 10 m below your starting position.
Your mass is 80 kg. Determine the rotational inertia and mass of the uniform 0.80 m radius flywheel you need to
buy.

What are you asking

Ineed the situations,in the question

Part of the text of the exercise is missing.complete text: "a semiconductor laser in a cd player has an output wavelength of 780nm and a power level of 0.10mw. how many photons strike the cd surface during the player of a cd 69 minutes in length? ? "solutionthe power is the energy per unit of time; the laser power is  , and it is applied for a time t of  . from the previous equation we can find the total energy delivered by the laser during this time: then we can find the frequency of the photons of the laser light. in fact, we know the relatioship between c (speed of light), f (frequency) and  (wavelength): using  and  , we getfrom this, we can find the energy carried by one single photon of this frequency: and finally, we can find the number of photons dividing the total energy delivered by the laser by the energy carried by one single photon: