If you begin with 40 grams of a radioactive isotope and end with 10 grams, how many half-lifes of the radioactive isotope have passed ?

grav potential energy

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2

answer a fan shaped mass of sediment deposited at the base of a mountain front do to an abrupt change in stream gradient;