Question

A body covers 24m in 5th s and 32m in 8th s. find the distance covered by body in 18s

Answer 1

we know that,

distance travelled in nth second = u + (a/2)(2n-1)

in 5th second,
24 = u + (a/2)(9)
u = 24 - (a/2)(9)           ----(i)

in 8th second,
32= u + (a/2)(15)
u = 32 - (a/2)(15)        ----(ii)

from (i) and (ii),
we get a = (8/3) m/s^2

putting value of a in (i),
On solving, we get u = 12 m/s

on 18th second (or n = 18),
s = u + (a/2)(2n-1)
on putting values of u, a, and n (solved above),
we get s = 58.88 metres