FYKOS Year 36 Series 2 Problem 2 — uncomfortable bus · FYKOS 36 #36.2.2

Physics · mechanics

Problem

Jarda wanted to watch a lecture on his laptop on the bus, so he put the laptop on a flip-up shelf of the seat in front of him. The shelf has a depth

h=18\,\mathrm{cm}

and is perpendicular to the vertical backrest. Jarda's laptop, which is

l=25\,\mathrm{cm}

wide, consists of a base weighing

M=1~200\,\mathrm{g}

, and a screen weighing

m=650\,\mathrm{g}

. Let us assume that both parts are of homogeneous density. What is the largest angle the laptop can open up without falling off the shelf?