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Snow Day Blog

Inelastic Collision : Conservation of Momentum


Today we went out in the snow to demonstrate the conservation momentum! My brother, Toby, helps to show an perfectly inelastic collision where energy is lost. It is a perfect inelastic collision because he picked me up, so that our two masses come together to have the same final velocity. 


To calculate momentum, I used the equation m1vi1 + m2vi2 = (m1+m2)vf, where m1 was Toby and m2 was me, and vi2 was equal to 0.
To find the masses, I used the conversion factor 1kg = 2.2 lb.
m1=77.73 kg
m2=61.36 kg


Next, I used Logger Pro to figure out what Toby's initial and final velocities were. Because the snow made it hard to move I ended up taking all of the averages of his velocities before 8.7 seconds (the time of the collision) and after the collision to determine a starting and ending velocity. 


You can clearly see the change in velocity that occurs at 8.7 seconds.

Using google sheets to find the sums and averages of the values of velocity before and after 8.7 seconds, it was found that: 

vi1=5.896 m/s
vi2=0 m/s
vf=2.16m/s

Next, I plugged all of these values into the conservation of Kinematic Energy equation (1/2mv^2=1/2mv^2) to find the amount of KE that was lost in the equation.


1/2(77.73)(5.896)^2 = 1/2(77.73+61.36)(2.16)^2
1,351.057 - KE = 324.469
1,026.588 J of KE were lost in this collision.

Also please enjoy my dog jumping on top of me and spraying snow everywhere. That is all. 


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