Question

A pebble of mass 0.05 kg is thrown vertically upwards Give the magnitude and direction of net force on the pebble (a) during its upward motion (b) during its downward motion (c) at the highest point where it is momentarily rest
Do your answers change if the pebble were thrown at an angle of say `45^(@)` horizontal direction lgnore air resistance .

Answer 1

Whenever a body is thrown vertically upwards or it moves vertically downwards
As `m = 0.05 kg and a = + 10 m//s^(2)`
`:.` In all the three cases `F = ma = 0. 05 xx 10 = 0.5 N` vertically downwards
If the pebble were thrown at an angle of `45^(@)` with the horizontal direction it will have horizontal and vertical components of velocity These components do not affect the force on the pebble . Hence our answers do not alter in any case However in case (c) the pebble will not be at rest It will have horizontal component of velocity at the highest point .