What is the total number of pounds of carbon dioxide that 2 trees remove from the air each year?
2 answers:
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A) d. 10T
When a charged particle moves at right angle to a uniform magnetic field, it experiences a force whose magnitude os given by
where q is the charge of the particle, v is the velocity, B is the strength of the magnetic field.
This force acts as a centripetal force, keeping the particle in a circular motion - so we can write
which can be rewritten as
The velocity can be rewritten as the ratio between the lenght of the circumference and the period of revolution (T):
So, we get:
We see that this the period of revolution is directly proportional to the mass of the particle: therefore, if the second particle is 10 times as massive, then its period will be 10 times longer.
B)
The frequency of revolution of a particle in uniform circular motion is
where
f is the frequency
T is the period
We see that the frequency is inversely proportional to the period. Therefore, if the period of the more massive particle is 10 times that of the smaller particle:
T' = 10 T
Then its frequency of revolution will be:
Answer:
B) the sound source moves towards you at 100 m/sec
Explanation:
The Dopper Effect is a phenomenon that occur when there is relative motion between an observer and a source of a wave. When this situation occurs, there is an apparent shift in frequency of the wave, as observed by the observer.
The apparent frequency observed by the observer is given by
where
f is the original frequency of the wave
f' is the apparent frequency
v is the speed of the wave
is the velocity of the observer (positive if moving towards the source of the wave, negative otherwise)
is the velocity of the source (negative if moving towards from the observer, positive otherwise)
In this problem, we want to find the scenario in which the sound frequency is higher.
We see that in all 4 scenarios, the sound source is moving: this means we have to find the scenario in which the denominator of the equation is smaller.
First of all, we notice the sound source moves towards the observer, is negative, so the denominator is higher: this means that the correct option must be either A or B.
Also, we notice that since is negative, a value larger in magnitude will mean a smaller denominator: therefore, the correct answer will be
B) the sound source moves towards you at 100 m/sec
Since this situation will make the denominator of the formula the smallest possible.