One is for far distance the other is for close range
The answer to this question is C
<span> The box is exerting a force of its weight. So we'll use W=mg (Note: you can use the notation F=ma, doesn't matter since weight IS a force.) We can call g negative since it's directed down towards the earth.
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<span>W = 5kg(-9.8 m/(s^2)) = -49 N
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<span>Thus, the box exerts a force of 49N downwards. </span>
We have to calculate the period when we know the frequency of a sound wave. Period and frequency are related quantities. They are reciprocal of each other.
T = 1/f, where T is the period ( in seconds ) and f is the frequency ( in Hz ).
T = 1/220 Hz;
Answer: T = 0.0045 s.
