Two students are on the roof of a building 29.4 m above the street. One student throws a rock vertically downward at 4.9 m/s. At the same time, the other student throws a ball vertically upward at 4.9 m/s. The second ball misses the roof on its way down. a) Calculate the difference in the time the rocks spend in the air.
b) Calculate the velocity of each rock as it strikes the ground.
c) Calculate the distance between the rocks 0.5 seconds after they are thrown.

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

3. dark matter

empty space could also be a simple vacuum