I really need help with this!! Will give brainliest if you help T^T
1 answer:
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Answer:
The pitch that he hears after the truck passes and is moving away is 819.6 Hz.
Explanation:
The pitch that he hears after the truck passes and is moving away can be calculated using the following equation:
Where:
: is the perceived frequency
: is the emitted frequency
: is the speed of sound = 340 m/s
: is the speed of the observer = 0 (he is not moving)
: is the speed of the fire truck
First, we need to find the speed of the fire truck. When it approaches the observer we have:
Hence, the speed of the fire truck is 25.05 m/s.
Now, we can calculate the pitch that the observer hears after the truck passes:
Therefore, the pitch that he hears after the truck passes and is moving away is 819.6 Hz.
I hope it helps you!
Answer:
300 J
Explanation:
First of all, we need to calculate the net force acting on the crate, which is given by:
where
F = 100 N is the horizontal push
is the force of friction
Substituting,
Now we can calculate the net work done on the crate:
where
d = 10 m is the displacement
Substituting,
According to the work-energy theorem, the kinetic energy gained by the crate is equal to the work done on it: therefore, the answer is 300 J.