Solving Homework: Speed of Mass on Wagon

[Alex.malh]

Homework Statement

There is a wagon (W) on wheels with a vertical pole of 2m. (mass 20kg)
On the top of that pole there is a rope pendulum with an attached mass (M) of 10kg and length 1m.
The starting position is a pendulum angle of 60°.

No friction taken into account.
What is the speed of the mass compared to the wagon the first time it passes the pole?

Homework Equations

Ep= m * g * h
Ek= m*v²/2

The Attempt at a Solution

1.
EM0= 10kg * 10 m/s² * (1m *cos60) = 50J
EW0= 0
2.
EM1= 10kg*VM²/2
EW1= (10kg+20kg) *VW²/2

50J=EM1+EW1

And now i don't know how to continue.

 

[Ellispson]

Homework Statement

There is a wagon (W) on wheels with a vertical pole of 2m. (mass 20kg)
On the top of that pole there is a rope pendulum with an attached mass (M) of 10kg and length 1m.
The starting position is a pendulum angle of 60°.

No friction taken into account.
What is the speed of the mass compared to the wagon the first time it passes the pole?

Homework Equations

Ep= m * g * h
Ek= m*v²/2

The Attempt at a Solution

1.
EM0= 10kg * 10 m/s² * (1m *cos60) = 50J
EW0= 0
2.
EM1= 10kg*VM²/2
EW1= (10kg+20kg) *VW²/2

50J=EM1+EW1

And now i don't know how to continue.

Conservation of linear momentum?

 

[Alex.malh]

Ok, thanks!
I made an error by summing the masses for EW1.
Solution is 3.87m/s for the interested.