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vovangra [49]
3 years ago
10

"You throw a small rock straight up from the edge of a highway bridge that crosses a river. The rock passes you on its way down,

9.00 s after it was thrown. What is the speed of the rock just before it reaches the water 21.0 m below the point where the rock left your hand
Physics
1 answer:
Dahasolnce [82]3 years ago
4 0

Answer:

  48.54 m/s

Explanation:

If the rock takes 9 seconds to reach your position after being thrown, it reaches its maximum height in 4.5 seconds.

The height the rock reaches above your position is ...

  h = (1/2)gt^2 = (4.9 m/s^2)(4.5 s)^2 = 99.225 m

This height is an additional 21 m above the water, so the maximum height above the water is ...

  99.225 m +21.0 m = 120.225 m

The velocity (v) achieved when falling from this distance is found from ...

  v^2 = 2gh

  v = √(2(9.8)(120.225)) = √2356.41 ≈ 48.543 . . . . m/s

The speed of the rock when it hits the water is about 48.54 m/s.

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What cities (more than 1) has many fronts
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Chattanooga - Chatype, London - Johnston, Berlin - BMF Change, Milan - Milano City, Eindhoven - Eindhoven, Stockholm - Stockholm Type, Minneapolis, and St. Paul - Twin. 
6 0
3 years ago
2.5 gram sample of a radioactive element was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific Test
kow [346]

Answer:

0.15625 grams

Explanation:

Half life: It is related to the decay of radioactive material. The duration in which  half of the material will be degraded/decayed. That means after half life 50% of the radioactive material will be left. Here the half life is 28 years.

Initial quantity of the sample: 2.5 grams.

After 28 years, the leftover quantity = 1.25 grams

After 56 years, the leftover quantity = 0.625 grams

After 84 Years, the leftover quantity = 0.3125 grams

After 112 years, the leftover quantity = 0.15625 grams

5 0
3 years ago
A two-dimensional section of the body is known as an
lesya692 [45]
Median plane ..........
7 0
3 years ago
Question 9 In an RC series circuit, ε = 12.0 V, R = 1.07 MΩ, and C = 2.66 µF. (a) Calculate the time constant. (b) Find the maxi
meriva

Answer:

a.) τ = 2.85 s b.) Q = 3.19 * 10^-5 C c.) t = 1.691 s

Explanation:

So we are told that it is a RC circuit. We are told Q = C V [1 - e^(-t/RC)] = 12.0 V, R =  1.07 MΩ and C = 2.66 µF.

a.) The time constant for RC circuit, τ = RC. Substituting our known values we get:

τ = RC where R = (1.07 * 10 ^ 6)Ω and C = (2.66 * 10 ^ -6) F

τ = (1.07 * 10 ^ 6)Ω * (2.66 * 10 ^ -6) F = 2.8462 s ≈ 2.85 s

τ = 2.85 s

b.) The relationship between capacitance, potential, charge is given:

Q = CV[1-e^{-t/RC} ]

The capacitor is fully charge when t approaches infinity, therefore:

Q =  \lim_{t \to \infty} a_n CV[1-e^{-t/RC} ]

When t approaches infinity, the term e becomes very small (e^-∞ = 0), therefore we can simplify the equation and plug in our values

Q = (2.66*10^{-6}) F * (12.0)V *[1 - 0] = 3.192 * 10^{-5}

Q = 3.19 * 10^-5 C

c.) Using the same equation as before, we can substitute Q in and solve for Q:

(14.3 * 10 ^ 6) C = (2.66*10^{-6})F *(12.0)V*[1-e^{-t/(2.85s)}]\\0.552 = e^{-t/(2.85s)}\\t = -1 * 2.85 * ln(0.552) \\t = 1.69120678 s

t = 1.691 s

Hope this helps! I'm not sure what the units you want, so convert to the desired units.

6 0
3 years ago
a force of 5 N extends a spring of natural length 0.5m by 0.01, what will be the length of the spring when the applied force is
vova2212 [387]

Answer:

L_new =L+x^2  = L_new = 0.54_m.

Explanation:

Given data:

Force in the first case,  

F_1 = 5N

Force in the second case,  

F_2 = 20 N

Natural length of spring,  

L= 0.5

Extension in the first case,  

x_1 = 0.01m

Let the force constant of the spring be k.

Thus,

F_1=kx_1

5 = k × 0.01  

⇒ k = 500 N/m.

The extension in the spring in the second case can be given as,

F_2=kx_2

20 = 500x_2

⇒ x_2 = 0.04 m.

Thus, the effective length of the spring would be,

L_new =L+x^2

L_new = 0.5+0.04

L_new = 0.54_m.

5 0
2 years ago
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