At some time (t = 0) mas of a Radon (Rn) [atomic number 86 and atomic mass number 222] sample is 0.38 µg. Half-life of Radon is 3.8235 days. Avogadro’s number = 6.02 x 1023. (a) Determine the initial number of nuclei in the sample
(b) Determine the initial activity of the sample
(c) Determine the number of nuclei present in the sample after 5.0 h

Mechanical energy is when the amount of kinetic and potential energies added together remains the same. conserved created lost

Consider two less-than-desirable options. in the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. in the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. which of these two situations would result in the greatest impact force?

Which of the following is part of the explanation or description of electromagnetic waves? (select all that apply) a. electrically charged molecules in a medium transfer their energy to nearby electrically charged molecules. b. a changing electric field causes a changing magnetic field. c. magnetic molecules in a medium transfer their energy to nearby magnetic molecules. d. a changing magnetic field causes a changing electric field.