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April 19, 2014

April 19, 2014

Posted by **Hester** on Monday, December 5, 2011 at 4:22pm.

1) If the maximum height of the block is ,h, is 35 cm, how fast was the bullet originally moving?

(can you explain the steps i'm really confused)

- AP Physics -
**Colin**, Sunday, April 7, 2013 at 3:26pmm1= mass of the bullet

m2= mass of the block

Vf=sqrt(2gh)

v1= initial velocity of bullet

v2= initial velocity of the block = 0

so

first is conservation of momentum

m1v1+m2v2=(m1+v2)Vf

solve for v1 (note m2v2=0)

v1=((m1+m2)/m2)/Vf

to find Vf look at conservation of energy

KE+PE=KE'+PE'

.5(m1+m2)Vf^2+0=0+(m1+m2)gh

Solve for Vf and you get Vf=Sqrt(2gh)

now v1=((m1+m2)/m2)/(sqrt(2gh)) and solve

v1= 15.715 m/s

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