Physic Labs

Problem 1

A body of mass m starts from rest on a frictionless track and descends a vertical height H, then moves onto a rough horizontal surface with kinetic-friction coefficient μ. The horizontal surface is long enough for the body to stop; take g=9.8 m/s² and neglect other resistance. (a) Find the speed on reaching the horizontal using mechanical-energy conservation. (b) Find friction and acceleration on the horizontal. (c) Determine stopping distance s using kinematics and confirm by work–energy. Use SI units throughout and treat components as ideal exactly as specified. State sign conventions when writing equations and retain units in final results.
μ>0;mass cancels because friction work μmgs balances mgH\mu>0; \text{mass cancels because friction work }\mu mgs\text{ balances }mgH
problems.proof.analysis

Collect results in the order asked. Dimensions and physical signs provide independent checks; they do not replace the derivation but can expose algebraic errors.