Can someone please check this modified pendulum velocity problem

[yamugushi]

[solved] Can someone please check this modified pendulum velocity problem

Homework Statement

I'm looking for the ballistic pendulum velocity for a simple machine (pull back lever, it shoots a marble into a block that raises to a certain degree measured)

I have the angle that the block is raised
length of the string
mass of block

Homework Equations

Ke=Pe (1/2MV^2=MGH)
cos@=length of sting - height/length of string

The Attempt at a Solution

.20cos25.3 = .20 - h

which gives me .02cm, which in turn gives me .6m/s, which seems a bit slow, I feel as if I'm messing up my trig but I don't know where...

I figured out I was using an incorrect derivation, I was just so fixed on thinking I had messed up my trig work

 

[jegues]

I'm confused in what you want us to check? What specific quantity are you concerned about?

The intial velocity of the object after its pulled back a certain distance?

 

[yamugushi]

I'm confused in what you want us to check? What specific quantity are you concerned about?

The intial velocity of the object after its pulled back a certain distance?

I've been given the manufacturers velocity, which is 5.5m/s, I'm getting less than 1m/s and honestly I don't see what I'm doing wrong.
BTW here is the pendulum I used:

 

[jegues]

What exactly is this:

V = Rad(9.8 * 0.2)/0.5

?

 

[yamugushi]

What exactly is this:

V = Rad(9.8 * 0.2)/0.5

?

Ke=Pe
1/2mv^2=mgh
masses cancel, divide both sides by .5
take the square root of both sides to get v=rad(GH)/.5

 

[denverdoc]

Just your notation--rad is confused with radians. $$\sqrt{}$$ is available on the latex option on advanced setting with the icon:$$\Sigma$$ Or simply denote as sqrt(gh/.5)