Answer:
very hard others will answer it
Explanation:
hard
The shaft is 78m approximately deep. The correct option is D which is 78 meters
<h3>
What are Sound Waves ?</h3>
Sound waves are longitudinal. That is, the direction of the waves is parallel to the direction of its propagation of particles.
Given that a boy finds an abandoned mine shaft in the woods, and wants to know how deep the hole is. He drops in a stone, and counts 4 seconds before he hears the "plunk" of the stone hitting the bottom of the shaft.
- The speed of the sound V = 330m/s
- The time it takes the sound to reach the top = t
Speed V = distance / time
330 = h/t
Make t the subject of formula
t = h/330
As the stone is dropped, initial velocity = 0, Using the formula
h = 1/2gT²
But T = 4 - t
T = 4 approximately
Substitute all the parameters
h = 1/2 × 9.8 × (4)²
h = 4.9 × (16)
h = 78.4m
Therefore, the shaft is 78m approximately deep. The correct option is D which is 78 meters
Learn more about sound wave here: brainly.com/question/16093793
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Answer:
Tech B
Explanation:
The control of electric actuators may be through through a two-wire or a five-wire circuit through the driver circuit by bidirectionally controlling via the motor wire polarity. The door position is determined by counting the actuator commutator pulses by the control module in the actuator with 2-wire, while the actuator with 5-wire uses potentiometer feedback.
The A/C ECU is the Air Condition Engine Control Unit.
The charge of one electron is 1.6 x 10⁻¹⁹ C
Number of electrons = (50 x 10⁻⁶) / 1.6 x 10⁻¹⁹
= 3.125 x 10¹⁴ electrons
The concepts used to solve this problem are sound power, area of ear drum, and inverse square law. First find the intensity 
using inverse square law for different distances. Then find the area of the ear drum using the diameter and finally find the energy transferred to each ear drum in one second. Intensity is inversely proportional to the square of the distance from the source:
Here,
r = Distance from the source,
Now the expression for the Area of ear drum is
The expression for Sound power is
Replacing,
Therefore the energy reached per second is 
