Question

De la ce inaltime minima trebuie sa alunece liber, fara frecare, un corp pentru a descrie o bucla de raza R?

Answer 1

$F_{cf}$=G+N
N=0⇒$F_{cf}$=G
$F_{cf}$=m*ω^2*r=(v/r)2*r=m*v^2/r
m*v^2/r=m*g
$E_{A}$=$E_{B}$
$E_{pA}$=$E_{Bp}$+$E_{BC}$
m*g*h=m*g*2r+(m*v^2)/2
v^2=2g*h-4r*g (1)
v^2=r*g (2)
din (1) si(2)⇒r*g=2*g*h-4*r*g⇒h=(r+4r)/2⇒h=5r/2