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Nesterboy [21]
3 years ago
15

The Chernobyl reactor accident in what is now Ukraine was the worst nuclear disaster of all time. Fission products from the reac

tor core spread over a wide area. The primary radiation exposure to people in western Europe was due to the short-lived (half-life 8.0 days) isotope 131I
131 I, which fell across the landscape and was ingested by grazing cows that concentrated the isotope in their milk. Farmers couldn't sell the contaminated milk, so many opted to use the milk to make cheese, aging it until the radiactivity decayed to acceptable levels. How much time must elapse for the activity of a block of cheese containing 131I 131 I to drop to 1.0% of its initial value?
Physics
1 answer:
Anna35 [415]3 years ago
5 0

Answer:

The correct answer is "53.15 days".

Explanation:

Given that:

Half life of 131_{I},

T_{\frac{1}{2} }= 8 \ days

  • Let the initial activity be "R_o".
  • and, activity to time t be "R".

To find t when R will be "1%" of R_o, then

⇒ R=\frac{1}{100}R_o

As we know,

⇒ R=R_o e^{-\lambda t}

or,

∴ e^{\lambda t}=\frac{R_o}{R}

By putting the values, we get

        =\frac{R_o}{\frac{R}{100} }

        =100

We know that,

Decay constant, \lambda = \frac{ln2}{T_{\frac{1}{2} }}

hence,

⇒ \lambda t=ln100

     t=\frac{ln100}{\lambda}

        =\frac{ln100}{\frac{ln2}{8} }

        =53.15 \ days  

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The Electric Potential of the Earth The Earth has a vertical electric field with a magnitude of approximately 100 V/m near its s
maksim [4K]

Answer:

16916.4 V

Explanation:

Electric potential: This is the work done in bringing a unit positive charge from infinity to that point in against the action of the field. The S.I unit  of Electric potential is V.

mathematically, Electric potential can be expressed as

P = E×d ....................................... Equation 1.

Where P = Electric potential, E = Electric Field, d = distance/height of the level at the top of the Washington  Monument.

Given: E = 100 V/m, d = 555 ft = 555×0.3048 m = 169.164 m.

Substitute into equation 1

P = 100×169.164

P = 16916.4 V.

Thus the potential difference = 16916.4 V.

4 0
3 years ago
(b) Suppose at a certain instant the kinetic energy is twice the elastic potential energy. Write an equation describing this sit
timurjin [86]

Answer:

1/2mv² = ke²

Explanation:

Let's suppose the material in question is a spring with spring constant k, mass m and position k, the kinetic energy possessed by the string will be;

K.E = 1/2mass×velocity² i.e 1/2mv²

Its elastic potential energy will be the work done on the spring when stretched which is equal to 1/2kx²

E.P = 1/2kx²

The equation describing the case where the kinetic energy is twice the elastic potential energy will be;

K.E = 2EP... 1)

Substituting the KE and EP formula into (1), we have;

1/2mv² = 2(1/2ke²)

1/2mv² = ke² which gives the required equation

8 0
4 years ago
If it takes a force of 20n to stretch a spring 0.1 meter how much energy does the spring have?​
V125BC [204]

Answer:

The energy stored in the spring would be 1 joule.

Explanation:

hope that helps?

8 0
3 years ago
What is the acceleration of a car going 50 mph that slows down to rest over 10 seconds?
VladimirAG [237]

Answer:

If the velocity is constant, then there is no acceleration. That is, the value of the acceleration is 0.

Explanation:

6 0
3 years ago
Thick rubber gloves prevent electric shock because​
Kaylis [27]

Answer:

Rubber is an insulator.

Explanation:

Rubber is an insulator. Electricity will always travel "the path of least resistance." Rubber has a very high resistance, so electricity will go somewhere else to find ground.

7 0
3 years ago
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