Answer:
The frequency of the piano string is either 1053 HZ or 1059 HZ.
Explanation:
Here we know that frequency of beats is equal to the difference between the frequencies between two waves .
Given that frequency of tuning fork is 1056 HZ .
Let the frequency of the piano be ' f ' .
Given that number of beats = 3.
We know that | 1056 - f | = 3 ;
⇒ 1056- f = ±3,
Upon solving this we get
f = 1056-3 and 1056 + 3
⇒ f = 1053 or 1059 .
Answer:
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Explanation:
A man walking at the rate of 5 km/hr. crosses a bridge in 15 minutes. The length of the bridge (in meters) is:
[A]1000 m
[B]1250 m
[C]600 m
[D]750 m
1250 m
Speed of the man = 5 km/hr

Time taken to cross the bridge = 15 minutes
Length of the bridge = Speed  Time

Hence option [B] is the right answer.
Option (d) is correct.
Explanation:
centripetal acceleration = a = r ω²
r= radius= 10 cm= 0.1 m
ω= angular velocity
9800= (0.1) ω²
ω=313 rad/sec
ω= 313 rad/s * (1 rev/2π rad)
ω=49.8 rev/s
They are blue because of hydrogen helium and methane