Muzzle Velocity by Analyzing Ballistic Pendulum

[ujellytek]

Homework Statement

Finding the equation for the muzzle velocity by using conservation of energy.

2. The attempt at a solution

Ek+Eg=Ek2+Eg2
Well I'm 100% sure the kinetic energy of the ball is transferred into the catcher. The displacement is 1.9cm which is 0.019m. Mb=0.0077Kg (mass of ball) Mc=0.085Kg (mass of catcher)

Here is my work: .5Mbv^2=Mc*g*h <- this is supposed to be the total mass because the Mc and Mb become one, right? (btw that's the method my classmates used)
My method: .5Mbv^2=(Mc+Mb)*g*h
eventually v=sqrt( (2*g*h*(Mc+Mb))/Mb )

3. Relevant questions:

Is the proper equation for the muzzle velocity? v=sqrt((2*g*h*(Mc+Mb))/Mb)

I went to check this online, and I found out that the equation is supposedly supposed to be
v=(1+Mc/Mb)*sqrt(2*g*h)

 

[gneill]

Your problem statement is rather spare. You should describe the setup and define the variables you'll be using.

Well I'm 100% sure the kinetic energy of the ball is transferred into the catcher.

You might want to rethink that. What type of collision is involved? What's conserved? What's not conserved?

 

[TomHart]

Also, you may just want to double check that all of the values are correct.