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zloy xaker [14]
3 years ago
7

Americium-241 is used in smoke detectors. It undergoes alpha decay with a half life of 432 years. The alpha particles ionize som

e of the air near the americium-241 source, and these charged ions are collected on a metal plate that has a small voltage applied to it. The collected particles cause a small electric current to flow in the detector. If smoke particles get in between the americium-241 source and the detector and reduce the current, the alarm is triggered. A typical smoke detector experiences 370000 alpha decays each second. How much time is needed for the number of decays to reduce to 93000 decays per second?
Physics
1 answer:
babymother [125]3 years ago
3 0

Answer:

860.6 years.

Explanation:

The parameters given are;

Initial detector activity = 370000 alpha decays per second

Final detector activity = 93000 alpha decays per second

Formula for time to change in activity is given by the following relation;

t_{93000} = \dfrac{-ln\dfrac{A}{A_0} }{\lambda} =  \dfrac{-ln\dfrac{93000}{370000} }{5.08 \times 10^{-11}} = 2.72 \times 10^{10} \, seconds

t₉₃₀₀₀ = 2.72 × 10¹⁰ seconds = 860.6 years.

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A ball is falling after rolling off a tall roof<br> The ball has what type of energy.
CaHeK987 [17]

Answer:

Linear and rotational Kinetic Energy + Gravitational potential energy

Explanation:

The ball rolls off a tall roof and starts falling.

Let us first consider the potential energy or more specifically gravitational potential energy (mgh; m = mass of the ball, g = acceleration due to gravity, h = height of the roof). This energy comes because someone or something had to do work to take the ball to the top of the roof against the force of gravity. The potential energy is naturally maximum at the top and minimum when the ball finally reaches the ground.

Now, the ball starts to roll and falls off the roof. It shall continue rotating because of inertia (Newton's first law). This contributes to the rotational kinetic energy (\frac{1}{2}I\omega^2; I=moment of inertia of the ball & \omega = angular velocity).

Finally comes the linear kinetic energy or simply, kinetic energy (\frac{1}{2}mv^2) which is caused due to the velocity v of the ball.

3 0
3 years ago
In the Bohr model of the atom, atomic electrons approximatately 'orbit' the nucleus. The hydrogen atom consists of a proton of m
lara31 [8.8K]

Answer:

F=3.61\times 10^{-47}\ N

Explanation:

Mass of a proton, m_p=1.67\times 10^{-27}\ kg

Mass of an electron, m_e=9.11\times 10^{-31}\ kg

The distance between the electron and the proton is, r=5.3\times 10^{-11}\ m

We need to find the mutual attractive gravitational force between the electron and proton. The gravitational force is given by :

F=G\dfrac{m_em_p}{r^2}

Where G is the universal Gravitational constant

F=6.67\times 10^{-11}\times \dfrac{9.11\times 10^{-31}\times 1.67\times 10^{-27}}{(5.3\times 10^{-11})^2}\\\\F=3.61\times 10^{-47}\ N

So, the force between the electron and proton is 3.61\times 10^{-47}\ N.

7 0
3 years ago
Objects 1 and 2 attract each other with a gravitational force of 12 units. If the mass of Object 2 is tripled, then the new grav
olasank [31]

Explanation:

Fgravity = G*(mass1*mass2)/D².

G is the gravitational constant, which has the same value throughout our universe.

D is the distance between the objects.

so, if you triple one of the masses, what does that do to our equation ?

Fgravitynew = G*(3*mass1*mass2)/D²

due to the commutative property of multiplication

Fgravitynew = 3* G*(mass1*mass2)/D² = 3* Fgravity

so, the right answer is 3×12 = 36 units.

5 0
2 years ago
What happens to the electrostatic force between two charged particles if the distance between them is doubled?
Stells [14]

According to Coulomb's Law , The size of the force varies inversely as the square of the distance between the two charges. So ,if the distance between the two charges is doubled, the  electrostatic force will become weak by one fourth of the original force.

5 0
3 years ago
The masses of the Moon and Earth are 7.35 x 1022 kg and 5.97 x 1024 kg, respectively. The strength of the gravitational force be
bixtya [17]

Answer:

Distance between centre of Earth and centre of Moon is 3.85 x 10⁸ m

Explanation:

The attractive force experienced by two mass objects is known as Gravitational force.

The gravitational force is determine by the relation:

F=\frac{Gm_{1} m_{2} }{d^{2} }      ....(1)

According to the problem,

Mass of Moon, m₁ = 7.35 x 10²² kg

Mass of Earth, m₂ = 5.97 x 10²⁴ kg

Gravitational force experienced by them, F = 1.98 x 10²⁰ N

Universal gravitational constant, G = 6.67 x 10⁻¹¹ Nm²kg⁻²

Substitute these values in equation (1).

1.98\times10^{20} =\frac{6.67\times10^{-11}\times7.35\times10^{22}\times5.97\times10^{24} }{d^{2} }

d^{2}=\frac{2.93\times10^{37}}{1.98\times10^{20}}

d=\sqrt{1.48\times10^{17}}

d = 3.85 x 10⁸ m

3 0
3 years ago
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