- a ball is thrown vertically upwards with initial velocity u .find distance covered by it in last t second.options are 1/2gt2or ut +1/2gt2 .
we have the following equivalence...
The distance covered by the ball during the last t seconds of its upward motion = The distance covered by it in first t seconds of its downward motion
now, during downward motion
s = ut + (1/2)at2
u = 0 [for first t seconds]
a = g
s = (1/2)gt2