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Can you guys check these calculations for me

  • #1
Background Information:
Clip Capacity of a Barret M82: 10 Rounds
Mass of a .50 Cal Round: 46.7 grams = .0467 Kg
Source: small arms by martin j. dougherty
Average Muzzle Velocity of a Barret M82 .50 Cal Rifle: 853 m/s
Average Specific heat capacity of normal human tissue: 3470 J/kg.C
http://www.engineeringtoolbox.com/human-body-specific-heat-d_393.html
Average Specific heat capacity of Adipose tissue: 2348J/kg.C
Source: http://www.itis.ethz.ch/itis-for-health/tissue-properties/database/heat-capacity/
Weight of Blob: 976 lbs = 442.7 Kg

Assumptions: Blob is around 75% adipose tissue(by weight) the remaining being normal body tissue. This means 332 Kg is adipose tissue. 110.6 Kg is other misc. body tissue.
Important Formula:
Kinetic Energy: Pe= ½mv2

Calculations:

Ke= 1/2 (.0467 Kg)(853 m/s)2 = 16.98 Kj = 16980 J

Joules needed to Raise blob 1 Degrees Celcius:
(332 Kg * 2348 J/Kg) + (2348J/Kg * 110.6 Kg)= 779536J + 259688J= 1039224 J = 1039 Kj
How much does Blob’s Temperature increase? : 19.98/ 1039 = .016 degrees Celcius
 

Answers and Replies

  • #2
CWatters
Science Advisor
Homework Helper
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Pe= ½mv2
That should be "KE" not PE but otherwise looks ok.

I made the KE of each round..

= 0.5 * .0467 * 8532 = 16.9 kJ not 19.98 kJ

There are 10 rounds so the energy is about 170 kJ.
 

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