Answer:
we can see that this time period is independent of the mass of the child so answer would be same if the child mass is different
Explanation:
Natural frequency of a simple pendulum of L length is given as
so the time period of the oscillation is given as
so we will have
also from above formula we can see that this time period is independent of the mass of the child so answer would be same if the child mass is different
(a) -83.6 Hz
Due to the Doppler effect, the frequency of the sound of the train horn appears shifted to the observer at rest, according to the formula:
where
f' is the apparent frequency
v = 343 m/s is the speed of sound
is the velocity of the source of the sound (positive if the source is moving away from the observer, negative if it is moving towards the observer)
f is the original frequency of the sound
Here we have
f = 350 Hz
When the train is approaching, we have
So the frequency heard by the observer on the platform is
When the train has passed the platform, we have
So the frequency heard by the observer on the platform is
Therefore the overall shift in frequency is
And the negative sign means the frequency has decreased.
(b) 0.865 m
The wavelength and the frequency of a wave are related by the equation
where
v is the speed of the wave
is the wavelength
f is the frequency
When the train is approaching the platform, we have
v = 343 m/s (speed of sound)
f = f' = 396.7 Hz (apparent frequency)
Therefore the wavelength detected by a person on the platform is