physics
posted by rex .
why is the following situation impossible? a normally proportioned adult walk briskly along a straight line in the +x direction, standing straight up and holding his right arm vertical and next to his body so that the arm does not swing. his right hand holds a ball at his side a distance h above the floor. when the ball passes above a point marked as x=0 on the horizontal floor, he opens his fingers to release the ball from rest relative to his hand. the ball strikes the ground for the first time at position x= 7.00 h.

yes, possible, given he and the ball had in initial velocity.
Time it takes to fall h meters:
h=1/2 g t^2
t=sqrt (2h/g)
velocity intial= distance/time= 7h/sqrt(2h/g)=
velocity initial= 1/sqrt(2/hg)
so if h initial= 1meter, then velocity
is 7/sqrt(1/4.9)= 7sqrt(4.9)= about 15m/s which is a really brisk walk. I cant run half that fast. 
Aplastic walk his two sides that measures 4 cm, 2 can, and 3 cm. it's mass is 19.2 g. Predict the block will float in water. Will it float in all of oil? Gather information before making a production.