Two scientists are experimenting with pure samples of isotope x, a highly radioactive substance. the first scientist has a sample with a mass of 20 grams. he measures a half-life of 232 seconds. the second scientist has a sample of the same substance with a mass of 80 grams. what is the half-life that she is most likely to measure?
a. 58 seconds
b. 232 seconds
c. 464 seconds
d. 928 seconds

In the first law of thermodynamics, triangle e=q-w, what does q stand for

Global warming will produce rising sea levels partly due to melting ice caps but also due to the expansion of water as average ocean temperatures rise. to get some idea of the size of this effect, calculate the change in length of a column of water 1.00 km high for a temperature increase of 1.00ºc. note that this calculation is only approximate because ocean warming is not uniform with depth. (answer in ×10^{-3} −3 m)

Atank has a shape of a cone with a radius at the top of 2 m and a height of 5 m. the tank also has a 1 m spout at the top of the tank. the tank is filled with water up to a height of 2 m. find the work needed to pump all the water out the top of the spout. (use 9.8 m/s2 for g and the fact that the density of water is 1000 kg/m3.)