Should the H/D Ratio Be Positive or Negative for Increased Neutron Leakage?

[richphys]

Homework Statement

A sphere has a height to diameter ratio of 1.00. The greater the surface area to volume ratio of a shape, the greater the neutron leakage.

To increase neutron leakage should H/D be positive or negative?

Homework Equations

H/D

The Attempt at a Solution

Positive? Good shapes are long cylinders.

 

[Astronuc]

Consider the surface area and volume of a sphere. Then consider the same for a cylinder.

The sphere has H = D, or H/D = 1. One could constrain a cylinder to H = D, but would that give the minimum surface area to volume? Compare with an infinite cylinder.

In part 1, "To increase neutron leakage should H/D be positive or negative?" is not valid. Think about H and D. What can we say about the values of H and D? Can either be negative?

There are certain values that are never negative, e.g., the number of real objects, like neutrons or particles, or sheep, absolute temperature. Negative numbers make no sense.

On the other hand, differences can be negative.