Compare and contrast power and work.
1 answer:
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Answer:
A gravitational force of 6841.905 newtons is exerted on the satellite by the Earth.
Explanation:
At first we assume that Earth is represented by an uniform sphere, such that the man-made satellite rotates in a circular orbit around the planet. Hence, the following condition must be satisfied:
(1)
Where:
- Period of rotation of the satellite, measured in seconds.
- Distance of the satellite with respect to the center of the planet, measured in meters.
- Gravitational constant, measured in newton-square meters per square kilogram.
- Mass of the Earth, measured in kilograms.
Now we clear the distance of the satellite with respect to the center of the planet:
(2)
If we know that ,
and
, then the distance of the satellite is:
The gravitational force exerted on the satellite by the Earth is determined by the Newton's Law of Gravitation:
(3)
Where:
- Mass of the satellite, measured in kilograms.
- Force exerted on the satellite by the Earth, measured in newtons.
If we know that ,
,
and
, then the gravitational force is:
A gravitational force of 6841.905 newtons is exerted on the satellite by the Earth.
The correct answer is:
Work is negative, the environment did work on the object, and the energy of the system decreases.
In fact, the work-energy theorem states that the work done by the system is equal to its variation of kinetic energy:
In this problem, the variation of kinetic energy is negative (because the final velocity is less than the initial velocity), so the work is negative, and this means that the environment did work on the object, and its energy decreased.