Assuming 70% of earth's surface is covered in water at an average depth of 2.5 mi, estimate the mass of the water on earth in kilograms.

When the velocity of an object is doubled, by what factor is its momentum changed? by what factor is its kinetic energy changed? a) the momentum is zero. b) the momentum is not zero. c) difficult to say.

Which type of reaction is shown in this energy diagram ?

Which scientist was the first to propose the heliocentric model of the universe? a. aristotle b. isaac newton c. galileo galilei d. nicolaus copernicus