How is the total energy of a system defined? write an appropriate formula for power using the dot notation. write a hamiltonian function representing an electron in the presence of a stationary positive point charge. clearly justify your function.

In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. the cylinder begins to rotate about a vertical axis. then the floor on which the passengers are standing suddenly drops away! if all goes well, the passengers will “stick” to the wall and not slide. clothing has a static coefficient of friction against steel in the range 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. part a what is the minimum rotational frequency, in rpm, for which the ride is safe? express your answer using two significant figures. f f = rpm

According to piaget’s stages of cognitive development, the child does not differentiate between self and other objects. the child repeats rewarding activities, discovers new ways to get what he or she wants, and may have imaginary friends. which period is described?

Aforce of 500.0 is represented graphically with its tail at the origin and the tip ointed in a direction 30.0° above the positive x-axis. what are the x- and y- components of the vector?