The sound was repeated because of the phenomenon of echo. The speed of sound in the metal is 800 m/s.
Echo results from the reflection of sound waves. The reason why a sound may be heard twice owes to the phenomenon of reflection which leads to echo.
To determine the speed of sound in the metal;
Length of metal = 1000 m
Time taken between the two sounds = 2.5 s
Using the formula;
V = 2d/t
V = 2(1000)/2.5
V = 800 m/s
To solve this problem we will apply the concepts related to energy conservation, so the potential energy in the package must be equivalent to its kinetic energy. From there we will find the speed of the package in the vertical component. The horizontal component is given, as it is the same as the one the plane is traveling to. Vectorially we will end up finding its magnitude. So,
Here,
m = Mass
g = Gravity
h = Height
v = Velocity
Rearranging to find the velocity
Replacing,
Using the vector properties the magnitude of the velocity vector would be given by,
Therefore the package is moving to 66.2m/s
<span>Young modulus E = stress/strain where E is the elastic modulus. We seek to calculate the the strain.
But we would have to get the stress first. Tensile stress = Force/Area. Force = 20100N. And the Area = 9.54* 13.9 = 132.606Nm^2.
Strain = stress/E.where E = 79. Hence we have 132.606/79 = 1.67</span>
Answer: the correct one is E .systems; for example, hurricanes could be prevented from forming by artificial "reefs" of precisely shaped marine platforms
Explanation:
(A) The portion after the semi-colon (for instance, ... platforms) is not a complete sentence.
(B) The portion after the semi-colon (for example, ... forming) is not a complete sentence.
(C) Which ... "reefs" ... prevent forming is unidiomatic; from is needed between prevent and forming. Prevent appears in the present tense, illogically implying that the artificial reefs—which don't yet exist, according to the earlier part of the sentence—already prevent the formation of hurricanes.
(D) The construction such as artificial "reefs" illogically implies that artificial reefs are weather systems. Additionally, the use of can in the present tense (as opposed to could) illogically implies that the artificial reefs—which don't yet exist, according to the earlier part of the sentence—do already exist.
(E) CORRECT. The semicolon is properly used to separate two complete sentences. Could is correctly used to describe a hypothetical consequence.
