Transit of tres-1. the planet tres-1, orbiting a distant star, has been detected by both the transit and the doppler tech- nique, so we can calculate its density and get an idea of what kind of planet it is. a. using the method of mathematical insight 13.3, calculate the radius of the transiting planet. the planetary transits block 2% of the star’s light. the star tres-1 has a radius of about 85% of our sun’s radius.

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?