Suppose the electric field in some region is found to be e = kr3 ˆr, in spherical coordinates (k is some constant). (a) find the charge density rho. (b) find the total charge contained in a sphere of radius r, centered at the origin. (do it two different ways.)

An implanted pacemaker supplies the heart with 72 pulses per minute, each pulse providing 6.0 v for 0.65 ms. the resistance of the heart muscle between the pacemaker’s electrodes is 550 ω. find (a) the current that flows during a pulse, (b) the energy delivered in one pulse, and (c) the average power supplied by the pacemaker.

What is the measure of how much matter is in an object and that can be measured using a balance? a. height b. volume c. weight d. mass

Could we see a galaxy that is 20 billion light-years away?