Physic Labs

Problem 1

A small block of mass mm is released from rest at the top of a fixed, smooth spherical dome of radius RR and slides down its outside; take gravitational acceleration gg as constant. The angle θ\theta is measured from the vertical through the top to the radius through the block, with 0≤θ<π/20\le\theta<\pi/2. Neglect the block's size and drag. (a) Use energy conservation to find its speed as a function of θ\theta. (b) Write Newton's second law radially and state the loss-of-contact condition. (c) Find the departure angle and explain why it is independent of m,R,gm,R,g.
mgcos⁡θ−N=mv2Rmg\cos\theta-N=\frac{mv^2}{R}
problems.proof.analysis

Choose inward as positive. The inward gravity component is mgcos⁡θmg\cos\theta, while the dome's normal force points outward; their difference gives centripetal acceleration v2/Rv^2/R.