How could I aggregate among multiple collections at once with loop?

Loop-the-loop minimum ht and acceleration?

• A small block of mass m = 1.2 kg slides, without friction, along the loop-the-loop track shown. the block starts from the point P at rest a distance h = 55.0 m above the bottom of the loop of radius R = 19.0 m. What is the kinetic energy of the mass at the point A on the loop? What is the magnitude of the acceleration of the mass at the point A of the loop? What is the minimum height h for which the block will reach point A on the loop without leaving the track? No picture, but basically there's a ramp with height H and at the bottom the ramp goes into a loop, with point A being at the top of the loop. Point P is where the block starts at height H. I found the answer to the first question, which is 199.92 J, but I can't seem to get the last two. Can anyone help? thanks.

• Answer:

  for the minimum h the centripetal and gravity must be equal at the top of the loop m*g*(h-2*R)=.5*m*v^2 where v^2/R=g m*g*(h-2*R)=.5*m*g*R h=.5*R+2*R=2.5*R =====================