Question

A 4.3 g mass is released from rest at C which has a height of 0.8 m above the base of a loop-the-loop and a radius of 0.31 m. The acceleration of gravity is 9.8 m/s2 . Find the normal force pressing on the track at A, where A is at the same level as the center

Answer 1

PE=KE+PE₁
mgH = mv²/2 + mgR
v²= 2g(H-R)
at point A
N=mv²/R =2mg(H-R)/R=
=2•4.3 •10⁻³•9.8•(0.8-0.31)/0.31 =
= 0.133 N

Answer 2

Elena is correct.