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Physics of Sound

  1. A body is executing S.H.M. When the displacements from the mean position are 4cm and 5 cm, the corresponding velocities of the body are 10 cm per sec and 8 cm per sec. Then the time period of the body is​
    1. 2π sec
    2. π/2 sec
    3. π sec
    4. (3π/2) sec
Correct Option: C

For S.H.M., Velocity,
v = ω √a² - x² at displacement x.
⇒ 10 = ω √a² - 16 ..........(1)
and 8 = ω √a² - 25 ..........(2)

Dividing ,
52
=
a2 - 16
=
25
42a2 - 2516

or , 16a2 - 256 = 25a2 - 625 ⇒ 9a2 = 369
∴ a2 =
369
9

Putting this value in equation (2) mentioned above,
10 = ω √{ (369 / 9) - 16 } ⇒ 10 = ω
225
9

or , ω =
10 × 3
= 2 radian / sec
15

Time period =
=
= π sec
ω2



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