What are the three ways of answering a scientific question

Several students in the group made comments to the coach about the back pack. which student has the correct analysis of the forces and motion of the back pack?

Work out sian speed for the first 30 minutes of her journey. give your answer in km/h.

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.