AP EAPCET 23-Aug-2021 Shift 1 Paper

Initial amplitude, Ai=A0
Final amplitude Af=0.9A0
Case 1 Time t1=5s
Case 2 Time t2=20s
Let, amplitude after 20s be A′.
As we know that,
A=A0e−α
∴0.9A0=A0e−5α
⇒e−5a=0.9
Again, A′=A0e−200
Now on powering Eq. (i) by 4 , we get
⇒(e−5α)4=(0.9)4
⇒e−20α=(0.9)4
∴ From Eq. (ii),
A′=A0e−200=A0(0.9)4 =0.6A0≈0.59A0