The first extra-solar planet around a main sequence star (i. e., not a neutron star or white dwarf) was found around the star 51 Pegasi in 1995. The large planet causes a measureable motion of the star around the center of mass of the system. Pegasi 51's orbital motion had a period of 4 days indicating a very large planet very close to the star. A large planet of mass M around a small star of mass 4M. The distance between planet and star is L. Both the planet and star will orbit around the center of mass of the system (marked by the red X). Required:
Where is the center of mass of the star-planet system?

Explain what it means to view something from a frame of reference. provide an example that illustrates your explanation. (4 points)

Cells in the nervous system have a potential difference of 70 mv across the cell membrane separating the interior of the cell from the extracellular fluid. this potential difference is maintained by ion pumps that move charged ions across the membrane. is this an emf? select the correct answer and explanation. 1)no. the ion pumps cannot separate charges; thus, they cannot create a potential difference. 2)yes. the ion pumps cannot separate charges, but they still can create a potential difference. 3)yes. the ion pumps can actively separate charge; thus, they can create a potential difference. 4)no. the ion pumps can separate charges, but they cannot create a potential difference.

Daughter element the new element produced along with a decay particle in a nuclear transmutation 2. half-life the substance that decays in a nuclear transmutation 3. parent element the change of one chemical element into another by nuclear decay or radioactive bombardment 4. transmutation the time required for the decay of one-half of the atoms in a sample of radioactive material