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.
Δh=R(1−cos⁡θ)\Delta h=R(1-\cos\theta)
problems.proof.analysis

The initial radius projects to height RR, while at angle θ\theta its vertical projection is Rcos⁡θR\cos\theta. The block therefore drops by R(1−cos⁡θ)R(1-\cos\theta).