Answer:
a. Light pollution refers to light used for human activities that brightens the sky and hinders astronomical observations.
Explanation:
Light pollution is due to the excessive and misdirected use of artificial light. Light bulbs are often design in an incorrect way, since a great part of its light is not completely directed to the ground and an important percentage is emitted to the sky in where will be scattered and reflected back to ground by the particles in the atmosphere. That brings as an effect a sky glow, therefore the visibility of astronomical objects will be extremely reduce.
Hence, professional astronomical research and amateur observations will be affected. Light pollution has a negative impact on bird migration at night and in the health of difference species, humans also.
The answer is: [C]: "4" .
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Note: To balance this equation, the coefficient, "4", should be placed in front of the PCl₃ ; and the coefficient, "6", should be placed in front of the Cl₂ .
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The balanced equation is:
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P₄ (s) + 6 Cl₂ (g) <span>→ 4 </span>PCl₃ (l) .
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Explanation:
The kinetic energy is said to be possessed due to the motion of the object. An object at rest will have zero kinetic energy and if it is in motion it will have some kinetic energy. The mathematical expression for kinetic energy is given by :
...........(1)
Where
m is the mass of the object
v is the velocity of object
It is clear form expression (1) that the kinetic energy of the object is directly proportional to the mass and velocity of an object.
So, the hypothesis for the mass and kinetic energy can be written as " when the mass of the object increases, its kinetic energy also increases because there exists a direct relationship between the mass and the kinetic energy of the object".
The magnitude of the average impulsive force imparted to the ball if it is in contact with the bat is 6000 N
The mass of the baseball, m = 0.15 kg
The speed at which it moves, v = 30 m/s
Time at which the baseball was in contact with the bat, t = 0.75 ms
t = 0.75/1000 s
t = 0.00075 s
The impulsive force is given by the formula:

Substitute m = 0.15 kg, v = 30, and t = 0.00075s into the formula above:

The magnitude of the average impulsive force imparted to the ball if it is in contact with the bat is 6000 N
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Answer:
the answer is B.
Explanation:
The claim is correct because Student Y can apply a force that is greater in magnitude than the frictional forces that are exerted on the student-student-skateboard system