A 16-kg sled is being pulled along the horizontal snow-covered ground by a horizontal force of 24 n. starting from rest, the sle
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Answer:
b) 472HZ, 408HZ
Explanation:
To find the frequencies perceived when the bus approaches and the train departs, you use the Doppler's effect formula for both cases:
fo: frequency of the source = 440Hz
vs: speed of sound = 343m/s
vo: speed of the observer = 0m/s (at rest)
v: sped of the train
f: frequency perceived when the train leaves us.
f': frequency when the train is getTing closer.
Thus, by doing f and f' the subjects of the formulas and replacing the values of v, vo, vs and fo you obtain:
hence, the frequencies for before and after tha train has past are
b) 472HZ, 408HZ
The power expended is 500 W
Explanation:
First of all, we start by calculating the work done by the man in order to ascend: this is equal to the gravitational potential energy gained by the man, which is
where
m = 50 kg is the mass of the man
is the acceleration of gravity
is the change in height
Substituting,
Now we can calculate the power expended, which is given by
where
W = 2500 J is the work done
t = 5 s is the time elapsed
Substituting, we find
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