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Helga [31]
2 years ago
6

A street light is mounted at the top of a 15-ft-tall pole. a man 6 ft tall walks away from the pole with a speed of 4 ft/s along

a straight path. how fast is the tip of his shadow moving when he is 30 ft from the pole?

Physics
1 answer:
Arlecino [84]2 years ago
5 0

Answer: 2.67 ft/s



Explanation:



1) The diagram with the triangle that represents the situation is in the image attached.


2) Similarity properties


(x + y) / 15 = y/6


⇒ 6(x+y) = 15y


⇒ 6x + 6y = 15y


⇒ 6x = 15y - 6y


⇒ 6x = 9y


⇒ y = 6x / 9


⇒ y = 2x / 3


3) Velocity is the derivative respecto to time. Then, find the derivative respect to time, t, on both sides


dy/dt = (2/3)dx/dt


4) The statement tells v = dx/dt = 4 ft/s


⇒ dy/dt = (2/3) 4 ft/s = (8/3)m/s ≈ 2.67 ft/s


Notice that this speed is constant, it does not depends upon the distance of 30 ft.

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Answer:

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Explanation:

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4 0
2 years ago
___ devices need constant power to operate. The timing functions are initiated by the presence or absence of a separate ""trigge
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Answer:

Solid-state

Explanation:

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A solid-state device such as a transistor, refers to a semiconductor component that is used to control the flow of voltage or current and as a gate (switch) for electronic signals. Thus, a transistor allows for the amplification, control and generation of electronic signals in a circuit.

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6 0
2 years ago
Stars within the halo move in random orbits that extend above and below the disk of the galaxy, while stars in the disk move in
Blizzard [7]
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4 0
3 years ago
Amy uses 20N of force to push a lawn mower 10 meters. How much work does she do? *
babunello [35]

She does 200J .

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4 0
3 years ago
In a lightning bolt, a large amount of charge flows during a time of 1.2 x 10-3 s. Assume that the bolt can be represented as a
ohaa [14]

Answer: 10.58 C has flowed during the lightning bolt

Explanation:

Given that;

Time of flow t = 1.2 × 10⁻³

perpendicular distance r = 21 m

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Now lets consider the expression for magnetic field;

B = u₀I / 2πr

the current flow is;

I = ( B × 2πr ) / u₀

so we substitute

I = ( (8.4 x 10⁻⁵) × 2 × 3.14 × 21 ) / 4π ×10⁻⁷

=  0.01107792 / 0.000001256

= 8820 A

Hence the charge flows during lightning bolt  will be;

q = It

so we substitute

q = 8820 × 1.2 × 10⁻³

q = 10.58 C

therefore 10.58 C has flowed during the lightning bolt

6 0
3 years ago
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