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## Homework Statement

Superman leaps in front of Lois Lane to save her from a volley of bullets. In a 1-minute interval, and automatic weapon fires 150 bullets, each of mass 8.0g, at 400 m/s. The bullets strike his mighty chest, which has an area of 0.75 m

^{2}. Find the average force exerted on Superman's chest if the bullets bounce back after an elastic, head-on collision.

## Homework Equations

Kinetic Theory of Gases: P = [tex]\frac{2}{3}[/tex]([tex]\frac{N}{V}[/tex])(.5mv^2)

where .5mv^2 is the average kinetic energy per molecule.

## The Attempt at a Solution

After substituting values into the Kinetic Theory of Gases:

P = [tex]\frac{2}{3}[/tex]([tex]\frac{N}{V}[/tex])(.5mv^2)

P = (2/3)(150 bullets/V)(.598.0g)(400m/s)^2

If V = 0.75m^2 * 1m = .75m^3, then P = 8.53 * 10^7 Pa.

However, the answer in the textbook is 16N, I'm just not sure if:

1. V (described above) is accurate.

2. There is an equation to relate work and pressure. (Note: This is a algebra-based course.)