Assume that for an 800 mhz or 800 000 000 hz magnet, all the 1h
nuclei would precess at frequencies between 800 008 500 hz and 799 991
500 hz. would a 10 μsec pulse would be short enough to ensure all the
nuclear spin vectors were tipped into the x-y plane? what is the longest
pulse that would be acceptable? )

photocells convert light energy to electricity

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.