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Paladinen [302]
3 years ago
7

A ball is thrown vertically upward from the ground. Its distance in feet from the ground in t seconds is s equals negative 16 t

squared plus 240 t. After how many seconds will the ball be 864 feet from the​ ground?
Physics
1 answer:
marishachu [46]3 years ago
4 0

Answer:

t₁ = 3 s

Explanation:

In this exercise, the vertical displacement equation is not given

        y = 240 t + 16 t²

Where y is the displacement, 240 is the initial velocity and 16 is half the value of the acceleration

Let's replace

      864 = 240 t + 16 t²

Let's solve the second degree equation

    16 t² + 240 t - 864 = 0

Let's divide by 16

    t² + 15 t - 54 = 0

The solution of this equation is

     t = [-15 ± √(15 2 - 4 1 (-54)) ] / 2 1

     t = [-15 ±√(225 +216)] / 2

     t = [-15 + - 21] / 2

We have two solutions.

     t₁ = [-15 +21] / 2

     t₁ = 3 s

     t₂ = -18 s

Since time cannot have negative values, the correct t₁ = 3s

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a brick is suspended above the ground at a height of 6.6 m. it has a mass of 5.3 kg. what is the potential energy of the brick
Svetradugi [14.3K]
The formula for potential energy is
E(p) = mgh

(Mass x gravity x height)

Therefore energy = (5.3)(9.8)(6.6)
= 342.8 J

How did I get 9.8?
9.8 is the constant for gravity
8 0
3 years ago
Which circle passes through more continents antarctic or arctic
Alex787 [66]

Answer:Arctic circle

Explanation:

Arctic circle is one of the circles of latitude. It is located at the northern region if the equator and passes through more than one continent. These continent includes: North Asia,

Northern America, and

Europe.

In these continent, it passes through eight known counties. These countries includes: Canada, Russia, Norway, Sweden, Finland, Denmark, Alaska and Iceland. It covers 4% of the Earth surface and it's climatic conditions are extreme.

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3 years ago
What is law of conservation of momentum ?​
Black_prince [1.1K]

Answer:

conservation of momentum, general law of physics according to which the quantity called momentum that characterizes motion never changes in an isolated collection of objects; that is, the to

8 0
2 years ago
A hollow cylinder with an inner radius of and an outer radius of conducts a 3.0-A current flowing parallel to the axis of the cy
Artemon [7]

Complete Question:

A hollow cylinder with an inner radius of 4.0mm and an outer radius of 30mm conducts a 3.0-A current flowing parallel to the axis of the cylinder. If the current density is uniform throughout the wire, what is the magnitude of the magnetic field at a point 12mm from its center?

Answer:

The magnitude of the magnetic field = 7.24 μT

Explanation:

Inner radius, a = 4.0 mm = 0.004 m

Outer radius, b = 30 mm = 0.03 m

Radius, r = 12 mm = 0.012 m

let h² = b² - a²

h² = 0.03² - 0.004²

h² = 0.000884

Let d² = r² - a²

d² = 0.012² - 0.004²

d² = 0.000128

Current I = 3A

μ = 4π * 10⁻⁷

The magnitude of the magnetic field is given by:

B = \frac{\mu I d^{2} }{2\pi r h^{2} } \\B =  \frac{4\pi * 10^{-7}   * 3* 0.000128^{2} }{2\pi *0.012* 0.000884^{2} }

B = 7.24 * 10⁻⁶T

B = 7.24 μT

7 0
3 years ago
A person of mass 55 kg swings on a rope length 4 m from rest (when the rope makes an angle of 30 degrees with the vertical) and
vovangra [49]

Answer:

θ = 19.66°

Explanation:

To determine the angle that the rope makes with the vertical for the two people, you first take into account the potential energy of the first person before he swings on the rope:

U=mgh

h: distance to the ground

g: gravitational acceleration = 9.8m/s^2

m: mass of the first person = 55 kg

In the image attache below you can notice that the height h is:

h=4-4cos(30\°)=0.53m

Then, the potential energy is:

U=(55kg)(9.8m/s^2)(0.53m)=285.67J

When the first person picks up the second person (when the rope is exactly vertical), all the potential energy becomes kinetic energy. Next, when both people reaches the maximum height h' the energy must be equal to the initial potential energy of the first person:

U'=(m_1+m_2)gh'=285.67\ J

From the previous equation you can get h':

h'=\frac{285.67J}{(55kg+70kg)(9.8m/s^2)}=0.2332m

Finally, you obtain the angle between the rope at the height h,' and the vertical, by calculating the following:

h'=4-4cos(\theta)\\\\\theta=cos^{-1}(\frac{4-h'}{4})=cos^{-1}(\frac{4-0.2332}{4})=19.66\°

hence, the angle between the rope and the vertical, when the two people are in the rope is 19.66°

8 0
3 years ago
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