Which Equation Best Describes the Block's Height After a Bullet Impact?

[Westin]

Homework Statement

Which equation could adequately be used to determine how high the block goes after being hit by the bullet (a height h)? (see figure) (m+M)gh+ksh=1/2(m+M)V^2
(m+M)gh+1/2ksh^2=1/2(m+M)V^2
(m+M)v+ksh=(m+M)V

Homework Equations

KE=1/2mv^2
Ugrav=Mgh
PE of spring = 1/2ks(s^2 final - s^2 initial)

The Attempt at a Solution

Based off of the equations, I believe the answer should be the second equation. I don't understand what else it could be..

I have only one attempt

 

[SammyS]

Homework Statement

Which equation could adequately be used to determine how high the block goes after being hit by the bullet (a height h)? (see figure)(m+M)gh+ksh=1/2(m+M)V^2
(m+M)gh+1/2ksh^2=1/2(m+M)V^2
(m+M)v+ksh=(m+M)V

Homework Equations

KE=1/2mv^2
Ugrav=Mgh
PE of spring = 1/2ks(s^2 final - s^2 initial)

The Attempt at a Solution

Based off of the equations, I believe the answer should be the second equation. I don't understand what else it could be..

I have only one attempt

Some of the variables in those equations need to be definrd for us.

I see L₁, m, v, and h in the figure.

What are k, s, M, V, an s without k ? Is that k_s rather than k⋅s ?

 

[paisiello2]

Maybe you could explain why you think it couldn't be the other two equations you excluded?

 

[Westin]

Maybe you could explain why you think it couldn't be the other two equations you excluded?

Because the other two equations are missing components to their equations

 

[Westin]

Some of the variables in those equations need to be definrd for us.

I see L₁, m, v, and h in the figure.

What are k, s, M, V, an s without k ? Is that k_s rather than k⋅s ?

1/2ks(s^2 final - s^2 initial)

ks = spring constant (k_s_)
(s^2 final - s^2 initial) = final stretch - initial stretch
v= velocity
m=mass1
M=mass2

 

[paisiello2]

Because the other two equations are missing components to their equations

And what components do these two equations have that are missing that the other one isn't?

 

[Westin]

And what components do these two equations have that are missing that the other one isn't?

(m+M)gh+ksh=1/2(m+M)V^2 the spring constant should be 1/2ksh^2 not ksh
(m+M)gh+1/2ksh^2=1/2(m+M)V^2
(m+M)v+ksh=(m+M)V Ugrav should be (m+M)gh instead of velocity multiplying the masses (m+M)v, also (m+M)V is missing V^2

 

[paisiello2]

I think you have your answer then.