The frequency of a wave is 50Hz. What is the period?
1 answer:
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Answer:
e) 120m/s
Explanation:
When the ball reaches its highest point, its velocity becomes zero, meaning
.
where is the initial velocity.
Solving for we get
which is the time it takes the ball to reach the highest point.
Now, after the ball has reached its highest point, it turns around and falls downwards. After time since it had reached the highest point, the ball has traveled downwards and the velocity
it has gained is
,
and we are told that this is twice the initial velocity ; therefore,
which gives
Thus, the total time taken to reach velocity is
This , we are told, is 36 seconds; therefore,
and solving for we get:
which from the options given is choice e.
Answer:
The sound intensity of train is 1000 times greater than that of the library.
Explanation:
We have expression for sound intensity level,
A train whistle has a sound intensity level of 70 dB
We have
A library has a sound intensity level of about 40 dB
We also have
Dividing both equations
The sound intensity of train is 1000 times greater than that of the library.