BITSAT 2019 Paper

(b) Amplitude of a damped oscillator
A = A0e−bt∕2m
Case 1:-
When t = 2 s, A =

A0

3

∴

A0

3

= A0e−2b∕2m ⇒

1

3

= e−b∕m ..........(i)
Case 2:-
When t = 6s, A =

A0

n

∴

A0

n

= A0e−6b∕2m ⇒

1

n

= (e−b∕m)3 ..........(ii)
From (i) and (ii)

1

n

=(

1

3

)3 ⇒ ∴ n = 33