Question

A particle of mass 3.00 kg is projected vertically upward with an initial velocity of 20.0 m/s. Neglecting air resistance, the particle’s kinetic energy when it is 20 m above the initial position is:

Answer 1

i need help

Answer 2

here taking u=20m/s
using v=u-at and finding the total time by taking v=0
we get T=2sec
now at 2sec the distance
S=ut-1/2at^2
thus S=(20)(2)-1/2(10)(4)
=40-20
=20m
thus 20m is its highest point
hence at highest point we know that entier kinetic energy turns into potential energy thus kinetic energy left is zero