<span>B.
many wavelengths pass a given point in one second
</span>
Heya!!
For calculate aceleration, lets applicate second law of Newton:

<u>Δ Being Δ</u>
F = Force = 4 N
m = mass = 36 kg
a = Aceleration = ?
⇒ Let's replace according the formula:

⇒ Clear acceleration and resolve it:

Result:
The aceleration is of <u>0,111 meters per second squared (m/s²)</u>
Good Luck!!
Answer: B. Nodes
Explanation:
Standing waves (so called because they seem to be immobile) occur when two waves interfere with the same frequency, amplitude but with different direction, along a line with a phase difference of half wavelength.
In these waves there are two types of points:
The <u>nodes</u>, which are points that remain motionless or stationary and do not vibrate. They are <u>due to the destructive interference of both waves when they meet. </u>
The antinodes, which are points that vibrate with a maximum vibration amplitude. They are <u>due to the non-destructive interference of both waves</u>.
Explanation:
A. Walk the person around