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Elza [17]
2 years ago
7

Sitting in a second-story apartment, a physicist notices a ball moving straight upward just outside her window. The ball is visi

ble for 0.20 s as it moves a distance of 1.19 m from the bottom to the top of the window. How long does it take before the ball reappears?
Physics
1 answer:
gregori [183]2 years ago
7 0

Answer:

1.013 s

Explanation:

You  can solve this problem using the equations for constant acceleration motion. The velocity at the bottom of the window can be found using this expression:

(x-x_o) = \frac{1}{2} at^2 + v_ot = -\frac{1}{2}gt^2 + v_ot

the gravity is negative as it opposes the movement.

(x-x_o) = -\frac{1}{2}gt^2 + v_ot\\v_o = \frac{(x-x_o)+\frac{1}{2}gt^2}{t} = \frac{1.19m+\frac{1}{2} 9.81m/s^2(0.2s)^2}{0.2s} = 6.931 m/s

Now, the time elapsed before the ball reappears is 2 times the time that it takes for the ball to go from the bottom of the window, reach maximum height, and reach again the bottom of the window, minus 2 times the time that it takes for the ball to travel from the top to the bottom of the window. The time that takes to the ball to reach maximum height, or in other words, to time that takes for the velocity of the ball to go from vo to 0m/s:

t_1 = \frac{0m/s - v_o}{g}  = \frac{-6.931 m/s}{-9.81m/s^2} = 0.706 s

Then:

t = 2t_1 - 2*0.2s = 2*(0.706s) - 0.4s = 1.013 s

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The correct answer is

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Explanation:

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2 years ago
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gizmo_the_mogwai [7]
To begin with, we can use the formula that links frequency, wavelength and velocity.

Because you already have the wavelength and the frequency, you just need to solve for velocity. You can do this by multiplying each side of the equation by frequency.

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Hope this helps :)

8 0
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What is the frequency of the most intense radiation emitted by your body? assume a skin temperature of 95 ∘f?
navik [9.2K]

Answer:    
Wien's law:    
λ_peak = b/T    
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elixir [45]

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