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Pie
2 years ago
8

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

Physics
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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The first ionization energy of a hydrogen atom is 2.18 aj (attojoules). what is the frequency and wavelength, in nanometers, of
jasenka [17]

1) Frequency: 3.29\cdot 10^{15}Hz

the energy of the photon absorbed must be equal to the ionization enegy of the atom, which is

E=2.18 aJ=2.18\cdot 10^{-18} J

The energy of a photon is given by

E=hf

where h=6.63\cdot 10^{-34}Js is the Planck's constant. By using the energy written above and by re-arranging thsi formula, we can calculate the frequency of the photon:

f=\frac{E}{h}=\frac{2.18\cdot 10^{-18} J}{6.63\cdot 10^{-34} Js}=3.29\cdot 10^{15} Hz


2) Wavelength: 91.2 nm

The wavelength of the photon can be found from its frequency, by using the following relationship:

\lambda=\frac{c}{f}

where c=3\cdot 10^8 m/s is the speed of light and f is the frequency. Substituting the frequency, we find

\lambda=\frac{3\cdot 10^8 m/s}{3.29\cdot 10^{15}Hz}=9.12\cdot 10^{-8} m=91.2 nm

5 0
2 years ago
What happens during the process of deposition
frez [133]
Deposition is the process in which sediments, soil and rocks are added to a landform or landmass. When previous weathers surface material , is deposited to a building layer of sediment .
8 0
3 years ago
A person is standing on a raft; their
krok68 [10]

Answer:

The volume of water displaced by the raft is 0.233 m³

Explanation:

The question relates to Archimedes' principle which states that the buoyant force experienced by an object immersed in a fluid is equal to the weight of (the force of gravity on) the displaced fluid

The given parameters are;

The combined mass of the person and the raft, m = 233 kg

The liquid on which the raft is located = Water

The density of water, \rho _{water} = 1000 kg/m³

Weight = Mass, m × g

Where;

m = The mass of the object

g = The acceleration due to gravity = 9.8 m/s²

Given that the raft is on the surface of the water (floating), the buoyant force is equal to the combined weight of the person and the raft = 233 kg

The combined weight of the person and the raft, W_{combined} = 233 kg × 9.8 m/s² = 2,283.4 N

Therefore;

The buoyant force = 2,283.4 N = The weight of the water displaced

The mass of the water displaced, m_{water}, = 2,283.4 N/(9.8 m/s²) = 233 kg

Density = Mass/Volume

The volume of water displaced by the raft = The mass of the water displaced/(The density of the water) = 233 kg/(1,000 kg/m³) = 0.233 m³.

3 0
2 years ago
Read 2 more answers
Which person is weightless?
ahrayia [7]

Answer: Option (b) is the correct answer.

Explanation:

The force of gravity acting on an object helps in determining the weight of an object. But a place where there will be no gravity or have zero gravitational pull then it means the person will be weightless.

For example, force of gravity on moon is zero which means any object or person on moon will be weightless.

On the other hand, when a child is in the air as she plays on a trampoline then it means gravitational pull form the earth is acting on it. So, it will definitely has some weight.

Similarly, a scuba diver exploring a deep-sea wreck is under the ground where there will be force of gravity. Hence, it will also have some weight.

Thus, we can conclude that an astronaut on the Moon is the person who is weightless.

7 0
3 years ago
Newton's third law can be summarized as "every action has an equal and opposite reaction". In this problem, consider the action
scoundrel [369]

Answer:

Action force: Would be the force of your feet against the Earth given by the weight defined as:

W = mg

Where g is a constat who represent the gravity g =9.8 m/s^2 in Earth

Reaction force: Would be the force of the Earth pushing against your feet. And on this case is represented by the normal force defined as:

N = \mu f_f

Where \mu represent the friction coefficient between the ground and the object.

And f_f the friction force.

If we don't have any other forces involved in the y axis we can conclude that:

W=N= mg

And as we can see we have that Action force = Reaction force

So then the third Law of Newton is satisfied.

Explanation:

For this case we have this:

Action force: Would be the force of your feet against the Earth given by the weight defined as:

W = mg

Where g is a constat who represent the gravity g =9.8 m/s^2 in Earth

Reaction force: Would be the force of the Earth pushing against your feet. And on this case is represented by the normal force defined as:

N = \mu f_f

Where \mu represent the friction coefficient between the ground and the object.

And f_f the friction force.

If we don't have any other forces involved in the y axis we can conclude that:

W=N= mg

And as we can see we have that Action force = Reaction force

So then the third Law of Newton is satisfied.

7 0
3 years ago
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