Answers

2016-02-17T19:50:55+05:30
40 => 60 s

1 s =>40/60 = 2/3 Hz = f

T = 1/f = 3/2 = 1.5 s

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2016-02-17T20:23:35+05:30
oscillation=40
time taken=60
in 1 sec = 40/60=2/3 Hz  
frequency = 1/time period
time period = 1/frequency
time period = 1/2/3 =3/2 =1.5 sec

i hope it helps...........
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