1. At a certain instant, a piece of radioactive material contains 10^12 atoms. The half-life of
the material is 30 days
1. Calculate the number of disintegrations in the
first second.
2.How long will elapse before 10^14 atoms remain?
3. What is the count rate at this time?​

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

The two required components for a generator are