Question

a ball dropped from a tower in the last sec. of its motion it travels a dist.15m . find the height of tower?

Answer 1

since
sn=u+a/2*(2n-1)
n = last second here.
time taken =root of(2h/g)
15=0+(10/2)×(2n-1)
3=2n-1
n=2
rootof(2h/g)=2
2h/g=4
h=2g
if you take g=10
h=20m
othewise
h=19.8m