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

Waves are used in many practical applications to support work, entertainment, and health. one example is the use of ultrasound imaging to safely track the development of a growing fetus. what is a specific example of a practical application of waves in medicine, entertainment, safety, or other fields? provide a brief explanation of how the properties of waves are useful to that application.

A14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.

What type of force holds atoms together in a crystal?