The components of a 15 meters per second velocity at an angle of 60 degrees above the horizontal are?
1 answer:
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<h2>Answers:</h2>
:
>>>><u>This case</u></h2>
(a) The kinetic energy of a body is that energy it possesses due to its movement and is defined as:
(1)
Where is the mass of the body and
its velocity.
In this specific case of the satellite, its kinetic energy taking into account its mass
is:
(2)
On the other hand, the velocity of a satellite describing a circular orbit is constant and defined by the following expression:
(3)
Where is the gravity constant,
the mass of the Earth and
the radius of the orbit <u>(measured from the center of the Earth to the satellite).
</u>
Now, if we substitute the value of from equation (3) on equation (2), we will have the final expression of the kinetic energy of this satellite:
(4)
Finally:
(5) >>>>This is the kinetic energy of the satellite
(b) According to Kepler’s 2nd Law applied in the case of a circular orbit, its Period is defined as:
(6)
Where is a constant and is equal to
. So, this equation in these terms is written as:
(7)
As we can see, <u>the Period of the orbit does not depend on the mass of the satellite </u>, it depends on the mass of the greater body (the Earth in this case)
, the radius of the orbit and the gravity constant.
(c) The gravitational force described by the law of gravity is a central force and therefore is <u>a conservative force</u>. This means:
1. The work performed by a gravitational force to move a body from a position A to a position B <u>only depends on these positions and not on the path followed to get from A to B. </u>
2. When the path that the body follows between A and B is a c<u>losed path or cycle</u> (as this case with a <u>circular orbit</u>), <u>the gravitational work is null or zero</u>.
<h2>This is because the gravity force that maintains an object in circular motion is a centripetal force, that is, <u>it always acts perpendicular to the movement</u>. </h2>
Then, in the case of the satellite orbiting the Earth in a circular orbit, its movement will always be perpendicular to the gravity force that attracts it to the planet, at each point of its path.
(d) The total Mechanical Energy of a body is the sum of its Kinetic Energy
and its Potential Energy
:
(8)
But in this specific case of the circular orbit, its kinetic energy will be expresses as calculated in the first answer (equation 5):
(5)
And its potential energy due to the Earth gravitational field as:
(9)
This energy is negative by definition.
So, the total mechanical energy of the orbit, also called the Orbital Energy is:
(10)
Solving equation (10) we finally have the Orbital Energy:
(11)
At this point, it is necessary to clarify that a satellite (or any other celestial body) orbiting another massive body, can describe one of these types of orbits depending on its Orbital Total Mechanical Energy :
-When :
We are talking about an <u>open orbit</u> in which the satellite escapes from the attraction of the planet's gravitational field. The shape of its trajectory is a parabola, fulfilling the following condition:
Such is the case of some comets in the solar system.
-When :
We are also talking about <u>open orbits</u>, which are hyperbolic, being
<h2>-When
We are talking about <u>closed orbits</u>, that is, the satellite will always be "linked" to the gravitational field of the planet and will describe an orbit that periodically repeats with a shape determined by the relationship between its kinetic and potential energy, as follows:
-Elliptical orbit: Although is constant,
and
are changing along the trajectory
.
-Circular orbit: When at all times both the kinetic energy and the potential
remain constant, resulting in a total mechanical energy
as the one obtained in this exercise. This means that the speed is constant too and <u>is the explanation of why this Energy has a negative sign.
</u>
Answer:
The anchor points are 78.37 ft and 111.99 ft
Explanation:
If you look at the attached (Fig 1) you will find that the union of antenna and its guy wires forms two right triangles. To solve problems that involve this kind of triangles, you can apply trigonometric functions (sine, cosine, etc) and Pythagoras Theorem. Trigonometric functions states the relation between angles, sides and hypotenuse of a right triangle. If you look Fig2, considering α angle, "b" is the opposite side, "a" the adjacent side and "c" the hypotenuse. Then
a) Sine (α) = b/c it means opposite side/hypotenuse
b) Cosine (α)= a/c, it means adjacent side/hypotenuse
c) Tangent (α) = b/a opposite side/adjacent side.
Pythagoras theorem states that if you called "a" and "b", the sides of the right triangle, and "c" the hypotenuse, then:
a² + b² = c²
As the problem states the lengths 150 ft and 170 ft represents the value of the hypotenuse of each triangle and 65° is one of the angles of the triangle with 150 ft hypotenuse. So you can solve this using sin (65°) to find the height of the antenna (h) and then the two distances (x and y,).
Sine (65°) = h/ 150 ft ⇒ Sine (65°) x 150ft = h ⇒ h = 127.9 ft.
To find x : Cosine (65°) = x/ 150 ft ⇒ Cosine (65°) x 150 ft = x
⇒ x = 78.37 ft.
And finally, to find y we can apply Pythagoras theorem
(170 ft)² = (127.9 ft)² + y² ⇒ y² = (170 ft)² - (127.9 ft)² ⇒ y = 111.99 ft
Summarizing, the anchor points are 78.37 ft and 111.99 ft
