Part A In the fall of 2002, a group of scientists at Los Alamos National Laboratory determined that the critical mass of neptunium-237 is about 60.0 kg. The critical mass of a fissionable material is the minimum amount that must be brought together to start a chain reaction. Neptunium-237 has a density of 19.5 g/cm³. What would be the radius r of a sphere of neptunium-237 that has a critical mass? Express your answer in centimeters to three significant figures. ▸ View Available Hint(s) r = 跖 ΕΠΙ ΑΣΦ 0 ? cm

Assume that the board you used was covered with two materials, material 1 and material 2. If the height where the wooden block started to slide down is higher on material 2 than on material 1, what can we say about the μs and μk associated with material 2 as compared to material 1? a. μs and μk on material 2 is higher than on material 1b. μs and μk on material 1 is higher than on material 2c. μs on material 2 is higher than on material 1, but  μk material 1 is higher than on material 2d. μs on material 1 is higher than on material 2, but  μk material 2 is higher than on material 1e. Regarless of any height,  μs and μk is same on material 1 and material 2

Please help. This problem involves finding the radius and volume of a platinum atom using its density. Thank you.

A student measures the mass of an object with a scale several times, resulting in an average mass m = 11.29 grams. Another student points out that the scale was not “zeroed”, or calibrated to read zero mass with no object on it, before the object was weighed. Without a load, the scale reads 0.08 grams. No one has used the scale since the last measurement.  c) What is the correct mass of the object?