Question on mechanics

Question on Motion:

A heavy metal hammer of mass 500kg is raised so that its bottom end is 4.00m above the top of the metal bar. The bar has negligible mass compared with that of the hammer. When the hammer is released it falls freely. On striking the metal bar the hammer remains in contact with it and the hammer moves down furthera 0.50m

Calculate the speed of the hammer at the instant it comes into contact with the bar.

Thanks a lot
From John Wood

Reply 1

Stranded

I think it should go like this:

PE lost=KE gained
mgh=1/2mv^2

PE lost= 500*10*4= 20000
KE gained= 20000
Hence 20000= 1/2*500*v^2
giving v^2= 80
So naturally v would be square root that.