N the fall of 2002, a group of scientists at Los Alamos National Observatory determined that the critical mass of neptunium - 237 is ab out 60.0 kg. (The critical mass of a fissionable material is the minimum amount that must be brought together to start a nuclear chain reaction.) Neptunium has a density of 19.5 g/cm 3 . What would be the radius of a sphere made of this material that has a critical mass

The membrane surrounding a living cell consists of an inner and an outer wall that are separated by a small space. assume that the membrane acts like a parallel plate capacitor in which the effective charge density on the inner and outer walls has a magnitude of 7.0 × 10-6 c/m2. (a) what is the magnitude of the electric field within the cell membrane? (b) find the magnitude of the electric force that would be exerted on a potassium ion (k+; charge = +e) placed inside the membrane.

Which of the following is not a part of the respiratory system? a. pharynx b. trachea c. pancreas d. larynx

Which diagram correctly demonstrates the various forces acting on a ball moving horizontally with some speed?