Classify which of the following is a substance: tablero salt, seawater or sand? explain how you know.

Explain what happens at the saturation point when adding salt to water at room temperature.

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.

Two cans on a sunny window one black and the other white construct and explanation of the effect of sun will have on both cans over a two hour period?