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3 years ago

One-eighth of an original radioactive sample will remain at the end of __________ half-lives

Physics

2 answers:

polet [3.4K]3 years ago

7 0

One eighth of an original radioactive sample will remain at the end of 3 half lives.

kow [346]3 years ago

6 0

Answer:

One-eighth of an original radioactive sample will remain at the end of THREE half-lives

Explanation:

As we know that half life is defined as the time after which a radioactive nuclei will remain half in the number as we compare it with the initial amount present in the sample.

So here let say initially sample contains N number of radioactive atoms

so after one half life we will have "N/2" present in that sample

after 2nd half life the number of nuclei again becomes half of the remaining

$N_1 = \frac{N}{4}$

now after 3rd half life we can say

$N_2 = \frac{N}{8}$

so here correct answer will be

One-eighth of an original radioactive sample will remain at the end of THREE half-lives

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HELP ASAP TIMED TEST

balu736 [363]

Answer:

Correct choice: b 4H

Explanation:

Conservation of the mechanical energy

The mechanical energy is the sum of the gravitational potential energy GPE (U) and the kinetic energy KE (K):

E = U + K

The GPE is calculated as:

U = mgh

And the kinetic energy is:

$\displaystyle K=\frac{1}{2}mv^2$

Where:

m = mass of the object

g = gravitational acceleration

h = height of the object

v = speed at which the object moves

When the snowball is dropped from a height H, it has zero speed and therefore zero kinetic energy, thus the mechanical energy is:

$U_1 = mgH$

When the snowball reaches the ground, the height is zero and the GPE is also zero, thus the mechanical energy is:

$\displaystyle U_2=\frac{1}{2}mv^2$

Since the energy is conserved, U1=U2

$\displaystyle mgH=\frac{1}{2}mv^2 \qquad\qquad [1]$

For the speed to be double, we need to drop the snowball from a height H', and:

$\displaystyle mgH'=\frac{1}{2}m(2v)^2$

Operating:

$\displaystyle mgH'=4\frac{1}{2}m(v)^2 \qquad\qquad [2]$

Dividing [2] by [1]

$\displaystyle \frac{mgH'}{mgH}=\frac{4\frac{1}{2}m(v)^2}{\frac{1}{2}m(v)^2}$

Simplifying:

$\displaystyle \frac{H'}{H}=4$

Thus:

H' = 4H

Correct choice: b 4H

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3 years ago

In diving to a depth of 248 m, an elephant seal also moves 296 m due east of his starting point. What is the magnitude of the se

Vinvika [58]

Answer:

The displacement is 386.16m

Explanation:

A seal dives to a depth of 248m. To find displacement, we must calculate the resultant vectors which will give us the displacement

R= sqrt(vector1+vector2)

Since this is a right angle triangle

R= sqrt(248^2 + 296^2)

R= sqrt(149120)

R= 386.16m

Displacement = 386.16m

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3 years ago

On a cold winter day, the flow of heat is from the outside in. A.True B.False

fredd [130]

Your answer s obviously false

8 0

3 years ago

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What are all stars made of

ivolga24 [154]

Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores. Aside from our sun, the dots of light we see in the sky are all light-years from Earth. They are the building blocks of galaxies, of which there are billions in the universe. It’s impossible to know how many stars exist, but astronomers estimate that in our Milky Way galaxy alone, there are about 300 billion.

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3 years ago

A 500 N force accelerates an object at 20 m s-2. What is its mass?

avanturin [10]

Answer: The mass of the object is 25kg.

The given question deals with Newton's second law of motion and its applications.

Explanation: Given force, F=500N

acceleration, a=20 m/ $s^{2}$

From Newton's 2nd law of motion , we have

F=ma where m=mass of the object

⇒500=m×20

⇒m=500/20=25

∴ Mass of the object is 25 kg .

Reference Link: brainly.com/question/1141170

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2 years ago