AP EAPCET 20-Aug-2021 Shift 1 Paper

Let initial velocity =u
Final velocity after passing one plank =u−

u

25

=

24

25

u
Number of planks =N
Final velocity of bullet, v=0ms−1
Acceleration of bullet =a
As we know that
v2−u2=2as
∴a=

v2−u2

2s

=

( 24 25 u)2−u2

2s

=−

49u2

625×2s

Again for 'N' number of planks,
02−u2=2(

49u2

625×2s

).Ns
⇒N=

625

49

=12.7≈13