How did black holes get their name

If a stone with an original velocity of 0 is falling from a ledgeand takes 8 seconds to hoybthe ground whays the final velocity of the stone

What is the measure of how much matter is in an object and that can be measured using a balance? a. height b. volume c. weight d. mass

Your friend increases her force on the desk by 30n . she doesn't change the direction of her push . what happens to the net force on the desk .will the desk accelerate