(a) 646.9 Hz
The formula for the Doppler effect is:
where
f = 600 Hz is the real frequency of the sound
f' is the apparent frequency
v = 345 m/s is the speed of sound
is the velocity of the observer (zero since it is stationary at the station)
is the velocity of the source (the train), moving toward the observer
Substituting into the formula,
(b) 20.1 m/s
In this case, we have
f = 600 Hz is the real frequency
f' = 567 Hz is the apparent frequency
Assuming the observer is still at rest,
so we can re-arrange the Doppler formula to find , the new velocity of the train:
and the negative sign means the train is moving away from the observer at the station.
Answer:
B equilibrium
Explanation:
The feedback mechanism is used to sense, monitor, restore and maintain a system. It can sense when a system is not at equilibrium, thereby tries to restore the equilibrium by negating changes.
So, The feedback mechanism tries to negate changes to restore the equilibrium of a system
Answer:
direction
Explanation:
because particles surround the bell, so when the bell vibrates, it causes particles surrounding it to vibrate back and forth vigorously. as these particles vibrate they collide with the neighbouring particles, passing on the energy.
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Vertical line from the centre of mass is inside the base of the tower.