A man of mass 85 kg runs up a flight of stairs of height 4.6 m in a time period of 12 s.
a) Calculate the man’s power rating when doing this.
b) A girl achieves a power rating of 70% of the man’s power rating wh en she scales the stairs in a time of 9.6 s. Calculate the mass of the girl.

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.