AP EAPCET 08-Jul-2022 Shift 2 Paper

The given Situation is show below

For Ist part of journey,
u=0,a=−g=−10ms−2.
‌s=−40m
Now using,
v2−u2=2as
we get,
v2−0=2×(−10)(−40)
⇒v2=800
And using
v=u+at,
we get;
v=0+at1,
or
v2=a2t12
⇒t12=

v2

a2

=

800

100

=8⇒t1=2√2
Now, for second part of journey,
u=0,a=−10m∕ s2,s=−80m
⇒v2−u2=2as⇒v2=2×(−10)(−80)=1600
And v=u+at2 gives,
v=at2⇒v2=a2t22
Hence, 1600=100×t22
or t2=4s
Time to complete last 50% part of the journey
=t2−t1=4−2√2≃1.17s