Answer:
Breaths per minute is a frequency. The period is its reciprocal.
Explanation:
In simple harmonic motion, a period (T) is the time taken for one point to start in a position and reach that position again, in other words to complete a cycle or lapse. In this case, a period is the time one takes from starting to inspire the air to releasing all of it from the lungs.
In simple harmonic motion, the frequency (f) is how many times a point completes a cycle or lapse in one unity of time (could be one second, one minute, one hour, etc). In this case, the frequency is how many times one breathes in one minute. This is the breathing rate, since it is breathings per minute. Breaths per minute is a frequency.
Period (T) and frequency (f) relate to each other in the following formulae:
or
.
Therefore, breaths per minute is a frequency, and since it is related to the period, we say the period is reciprocal to it.
Answer:
C
Explanation:
There's a reason newton's 3rd law is called action-reaction :D
A - 1st law/inertia
B - 2nd law/f=ma
Answer:
acceleration = 1.79 m/s^2
Tension = 6817 N
Explanation:
First let's find Elizabeth's weight:

Her weight is greater than the normal force (N = 450 N), so the elevator is going downwards.
The acceleration of Elizabeth is given by:

Where P is the weight of Elisabeth, N is her normal force, m is her mass and a is the acceleration. Then, we have that:


The tension in the cable is given by:

In this case, we use the total mass, so we have:


The kinetic Energy has to be the same as the Energy with which the spring was stratched:
1/2×m×v^2=1/2×D×s^2
Ekin=1/2×440×0.3^2= 1/2×440×0.09=19.8. ( Of course, the kinetic Energy is normally Not calculated Like this , but in this case both Formulas have the Same solution so you can Wright it Like This)
By the way, if the spring Had Not reached its Natural length yet, you wouldnt be right if you calculate it Like above, because a Part of the Energy is still in the spring : Espring=Ekin+Espring2