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2 years ago

8

What is the definition of the half-life of a radioactive isotope?

2 answers:

Illusion [34]2 years ago

5 0

Answer:Half-life is the amount of time it takes for the initial mass of the isotope to decompose, by half, into other lighter atoms.

Explanation:Different radioactive isotopes have different half-lives. For example, the element technetium-99m has a half life of 6 hours. This means that is 100 kg of the element is left to decay, in 6 hours, 50kg of the mass will have changed into other elements/atoms. The half-life of uranium-238 is 4.5 billion years while that of polonium-216 is only 0.145 seconds.

Mashcka [7]2 years ago

4 0

Answer:

A. The time it takes for half the parent nuclei in a sample to become

daughter nuclei

:)

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A forklift pushes a box with a force of 500 N across the floor for a distance of 5.0 m, then turns around and pushes with the sa

yanalaym [24]

Answer:

5,000J

Explanation:

Work = Force x Distance

Distance back and forth is canceled out, so either the answer is + or -

5.0m + 5.0m = 10.0m

500N x 10.0m = 5,000J

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2 years ago

Each second, 1250 m3 of water passes over a waterfall 150 m high. Three-fourths of the kinetic energy gained by the water in fal

mote1985 [20]

Answer:

The generator produces electrical energy at a rate of 1378125000 J per second.

Explanation:

volume of water falling each second is 1250 $m^{3}$

height through which it falls, h is 150 m

mass of 1 $m^{3}$ of water is 1000 kg

⇒mass of 1250 $m^{3}$ of water, m = 1250×1000 = 1250000 kg

acceleration due to gravity, g = 9.8 $\frac{m}{sec^{2} }$

in falling through 150 m in each second, by Work-Energy Theorem:

Kinetic Energy(KE) gained by it = Potential Energy(PE) lost by it

⇒KE = mgh

= 1250000×9.8×150 J

= 1837500000 J

Electrical Energy = $\frac{3}{4}$ (KE)

= $\frac{3}{4}$ ×1837500000

= <u>1378125000 J per second</u>

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2 years ago

Before it enters earths atmosphere, what type of force is acting on a spacecraft returning from the moon to earth?

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D. Gravitational force

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2 years ago

Read 2 more answers

A certain factory whistle can be heard up to a distance of 2.5 km. Assuming that the acoustic output of the whistle is uniform i

enyata [817]

Answer:

Emitted power will be equal to $7.85\times 10^{-5}watt$

Explanation:

It is given factory whistle can be heard up to a distance of R=2.5 km = 2500 m

Threshold of human hearing $I=10^{-12}W/m^2$

We have to find the emitted power

Emitted power is equal to $P=I\times A$

$P=I\times 4\pi R^2$

$P=10^{-12}\times 4\times 3.14\times 2500^2=7.85\times 10^{-5}watt$

So emitted power will be equal to $7.85\times 10^{-5}watt$

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2 years ago

What is the pressure exerted by a block of wood of mass 10 kg with an area of 0.1 m2

koban [17]

Answer:

0.01

Explanation:

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2 years ago