Question

A body starting with an initial velocity of 3.5m/s and moving with uniform acceleration of 0.75m/s square undergoes displacement 111/8 in how much time

Answer 1

Here u = 3.5m/s
d = 111/8m
a= 0.75m/s2
t=?
as we know d = ut+1/2ft square
therefore, 111/8 = 3.5t + (1/2)0.75t^2
or 111/8 = (35/10)t + (1/2)*(75/100)t^2
or 111/8 = 7t/2 + 3t^2/8
or 111/8 = (28t+3t^2)/8
or 3t^2 + 28t - 111=0
or 3t^2 + 37t-9t-111=0
or t(3t+37) - 3(3t+37)=0
or (t-3)*(3t+37)=0
or t=3 sec or -37/3
as t can be zero hence t = 3second Ans.