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shtirl [24]
2 years ago
8

How long will it take a sample of lead-212 (which has a half-life of 10.64 h) to decay to one-eighth its original strength?

Physics
1 answer:
Valentin [98]2 years ago
5 0

Answer:

31.92 h

Explanation:

We'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:

Original amount (N₀) = 1

Amount remaining (N) = ⅛

Number of half-lives (n) =?

N = 1/2ⁿ × N₀

⅛ = 1/2ⁿ × 1

Cross multiply

2ⁿ = 8

Express 8 in index form with 2 as the base.

2ⁿ = 2³

n = 3

Thus, 3 half-lives has elapsed.

Finally, we shall determine the time. This can be obtained as follow:

Half-life (t½) = 10.64 h

Number of half-lives (n) = 3

Time (t) =?

n = t / t½

3 = t / 10.64

Cross multiply

t = 3 × 10.64

t = 31.92 h

Therefore, it will take 31.92 h for lead-212 to decay to one-eighth its original strength.

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Answer: 0.01 m

Explanation: The formulae for capillarity rise or fall is given below as

h = (2T×cosθ)/rpg

Where θ = angle mercury made with glass = 50°

T = surface tension = 0.51 N/m

g = acceleration due gravity = 9.8 m/s²

r = radius of tube = 0.5mm = 0.0005m

p = density of mercury.

h = height of rise or fall

From the question, specific gravity of density = 13.3

Where specific gravity = density of mercury/ density of water, where density of water = 1000 kg/m³

Hence density of mercury = 13.3×1000 = 13,300 kg/m³.

By substituting parameters, we have that

h = 2×0.51×cos 50/0.0005×9.8×13,300

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h = 0.01 m

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3 years ago
What is the most commonly used reference point
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Answer:

El punto de referencia más usado es el NORTE. Los puntos de referencia sirven para orientarnos, de esta manera podemos saber nuestra ubicación y luego desplazarnos. En este caso tenemos que el punto cardinal NORTE es el más usado, se tiene como referencia universal para lograr ubicarnos.

Explanation:

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2 years ago
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Trey races his bicycle for 192m. A wheel of his bicycle turns 48 times as the bicycle travels this distance. What is the diamete
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Answer:

1.27 m

Explanation:

Distance = 192 m

number of rotations = 48

Distance traveled in one rotation = 2 x π x r

Where, r be the radius of wheel.

so, distance traveled in 48 rotations = 48 x 2 x 3.14 x r

It is equal to the distance traveled.

192 = 48 x 2 x 3.14 x r

r = 0.637 m

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A grindstone increases in angular speed from 6.00 rad/s to 12.20 rad/s in 16.00 s. Through what angle does it turn during that t
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Answer:

Explanation:

Given that the grand stone has initial angular velocity of

w(ini)= 6rad/

And it has a final angular velocity of

w(fin)=12.20rad/sec

Time taken is t=16s

Using equation of angular motion

To get angular acceleration (α)

w(fin)=w(ini)+αt

12.20=6+16α

16α=12.20-6

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Angle that he turn using

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