A radar receiver indicates that a pulse return as an echo in 20 μs after it was sent. The reflecting object would be 3000 m away .
Phenomenon of hearing back our own sound is called an echo. It is due to successive reflection of sound waves from the surfaces or obstacles of large size. To hear an echo, there must be a time gap of 0.1 second in original sound and the reflected sound.
Given
time = 20 μs = 20 * 
s
let distance to the reflecting surface be = x
total distance travelled by pulse will be = 2x
speed = 3.0 × 
m/s
distance = speed * time
2x = 3.0 × * 20 *
x = 3000 m
The reflecting object would be 3000 m away
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Answer:
w = 706.32 [N]
Explanation:
The force due to gravitational acceleration can be calculated by means of the product of mass by gravitational acceleration.
w = m*g
where:
w = weight [N] (units of Newtons)
m = mass = 72 [kg]
g = gravity acceleration = 9.81 [m/s²]
Then we have:
![w = 72*9.81\\w = 706.32 [N]](https://tex.z-dn.net/?f=w%20%3D%2072%2A9.81%5C%5Cw%20%3D%20706.32%20%5BN%5D)
Answer:
Everyone is held accountable to the same laws, and those laws protect our fundamental rights. This is the foundation of the rule of law in the United States. We need new laws because life and the world keep revolving and changing. We therefore need new laws to match the latest trending events in the country.
I believe the correct answer from the choices listed above is option D. The <span>second law of thermodynamics</span> states that the entropy of a closed system must always increase. Hope this answers the question. Have a nice day.
Answer:
W = 157.5kJ
Explanation:
Assuming it moves the container at constant speed, the work done by the crane will be equal to the variation of the potential gratitational energy on the container:
where h2= -8m and h1=0m
Wc = 157.5kJ
