2damnold4this
New member
This
Help me out with the math here fellas
- Thread starter Clay
- Start date
This
Boy, you fellas sure took off with this. LOL
This was for a 6th grade science fair project. We were testing ice blocks vs pykrete (google it if you want to know what it is!) to see if the pykrete truly was stronger. All I wanted to do was give a "rough" estimation of how much energy each bullet delivered and show the math. I was able to find it and then help my son understand it all. He presented everything and was able to show the math. He got a perfect 100.
And FYI, the ice brick split apart with just the 22. The Pykrete was only chipped by the 22 and 9mm. The 44 took a small chunk of the pykrete brick, but the "whole" remained in tact. Pretty strong stuff!
This was for a 6th grade science fair project. We were testing ice blocks vs pykrete (google it if you want to know what it is!) to see if the pykrete truly was stronger. All I wanted to do was give a "rough" estimation of how much energy each bullet delivered and show the math. I was able to find it and then help my son understand it all. He presented everything and was able to show the math. He got a perfect 100.
And FYI, the ice brick split apart with just the 22. The Pykrete was only chipped by the 22 and 9mm. The 44 took a small chunk of the pykrete brick, but the "whole" remained in tact. Pretty strong stuff!
HelterSkelter
Moderator
DO IT THIS WAY
you need to record the average speed for the bullet in meters per second.
then you need to convert grains to grams, this site will help: http://www.metric-conversions.org/weight/grains-to-grams.htm
then convert grams to kilograms
then you need to plug the values in to the ke formula
m= mass in kilograms
v= speed of bullet
.5 X m X v X v = kinetic energy
this formula will give you the energy in joules, if you want to convert it to foot pounds multiply by .738.
also don't forget to use sig figs, if you have 240 grains as a weight you have 2 sig figs. this means if you get a speed of 1442 fps you will need to round that too 1400 before converting it to meters per seconds and you will multiply by .738 to get your final answer. if you don't do this you will get an answer that is more precise than your measurements and will be inaccurate.
and yeah, pykrete is way stronger since the water molecules have something to latch onto, it keeps fracture lines from forming in the crystal structure of the ice block and it splitting open.
you need to record the average speed for the bullet in meters per second.
then you need to convert grains to grams, this site will help: http://www.metric-conversions.org/weight/grains-to-grams.htm
then convert grams to kilograms
then you need to plug the values in to the ke formula
m= mass in kilograms
v= speed of bullet
.5 X m X v X v = kinetic energy
this formula will give you the energy in joules, if you want to convert it to foot pounds multiply by .738.
also don't forget to use sig figs, if you have 240 grains as a weight you have 2 sig figs. this means if you get a speed of 1442 fps you will need to round that too 1400 before converting it to meters per seconds and you will multiply by .738 to get your final answer. if you don't do this you will get an answer that is more precise than your measurements and will be inaccurate.
and yeah, pykrete is way stronger since the water molecules have something to latch onto, it keeps fracture lines from forming in the crystal structure of the ice block and it splitting open.
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