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2 years ago

A radioactive source has a half life of 80s.

1 answer:

6 0

Lets make the original number of nuclides at the start is 100.

If 7/8 of 100 is decayed, that means 87.5 decayed.

$\frac{7}{8} \times 100 = 87.5$

And there is 1/8 left of the number of nuclide 100. Which is 12.5

$100 - 87.5 =12.5$

$\frac{1}{8} \times 100 = 12.5$

How many Half lifes passed for 100 to become 12.5 is 3 Half-Lives.

$100 \div 2 \div 2 \div 2 = 12.5$

Each Half-Life is 80 seconds so there is 240 seconds

$3 \times 80 = 240$ The answer is that it takes 240 seconds.

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Two thermometers are calibrated, one in degrees Celsius and the other in degrees Fahrenheit.

sdas [7]

Answer:

The temperature is 233.15 K

Explanation:

Recall the formula to convert degree Celsius (C) into Fahrenheit (F):

$\frac{9}{5} C+32=F$

So if we want the value of degree C to be the same as the value of the degree F, we want the following: C = F

which replacing F with C on the right hand side of the equation above, allows us to solve for C:

$\frac{9}{5} C+32=F\\\frac{9}{5} C+32=C\\\frac{9}{5} C-\frac{5}{5} C =-32\\\frac{4}{5} C==32\\C= \frac{-32\,*\,5}{4} \\C=-40$

This means that -40°C = -40°F

And this temperature in Kelvin is:

-40°C + 273.15 = 233.15 K

8 0

2 years ago

An electron moves with a constant horizontal velocity of 3.0 × 106 m/s and no initial vertical velocity as it enters a deflector

Ghella [55]

Answer:

a = 5.05 x 10¹⁴ m/s²

Explanation:

Consider the motion along the horizontal direction

$v_{x}$ = velocity along the horizontal direction = 3.0 x 10⁶ m/s

t = time of travel

X = horizontal distance traveled = 11 cm = 0.11 m

Time of travel can be given as

$t = \frac{X}{v_{x}}$

inserting the values

t = 0.11/(3.0 x 10⁶)

t = 3.67 x 10⁻⁸ sec

Consider the motion along the vertical direction

Y = vertical distance traveled = 34 cm = 0.34 m

a = acceleration = ?

t = time of travel = 3.67 x 10⁻⁸ sec

$v_{y}$ = initial velocity along the vertical direction = 0 m/s

Using the kinematics equation

Y = $v_{y}$ t + (0.5) a t²

0.34 = (0) (3.67 x 10⁻⁸) + (0.5) a (3.67 x 10⁻⁸)²

a = 5.05 x 10¹⁴ m/s²

7 0

2 years ago

4. A 505-turn circular-loop coil with a diameter of 15.5 cm is initially aligned so that

Basile [38]

The strength of the magnetic field is $4.8\cdot 10^{-5} T$

Explanation:

According to Faraday's Law, the magnitude of the induced emf in the coil is equal to the rate of changeof the flux linkage through the coil:

$\epsilon = \frac{N\Delta \Phi}{\Delta t}$ (1)

where

N = 505 is the number of turns in the coil

$\Delta \Phi$ is the change in magnetic flux through the coil

$\Delta t = 2.77 ms = 2.77\cdot 10^{-3} s$ is the time interval

$\epsilon = 0.166 V$

The coil is rotated from a position perpendicular to the Earth's magnetic field to a position parallel to it, so the final flux is zero, and the magnitude of the flux change is simply equal to the initial flux:

$\Delta \Phi = B A cos \theta$

where

B is the strength of the magnetic field

A is the area of the coil

$\theta=0^{\circ}$ is the angle between the normal to the coil and the field

The area of the coil can be written as

$A=\pi r^2$

where

$r=\frac{15.5 cm}{2}=7.75 cm = 7.75\cdot 10^{-2} m$ is its radius

Substituting everything into eq.(1) and solving for B, we find:

$\epsilon= \frac{NB\pi r^2 cos \theta}{\Delta t}\\B=\frac{\epsilon \Delta t}{\pi r^2 cos \theta}=\frac{(0.166)(2.77\cdot 10^{-3})}{(505)\pi (7.75\cdot 10^{-2})^2(cos 0^{\circ})}=4.8\cdot 10^{-5} T$

Learn more about magnetic fields:

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8 0

2 years ago

Read 2 more answers

Elements in group 2 are all called alkaline earth metals. What is most similar about the alkaline earth metals? how many protons

Rom4ik [11]

Elements in group 2 are called alkaline earth metals, the most similarity about the alkaline metals is which chemical properties they have.

<h2>Further Explanation </h2><h3>Periodic table </h3>

Periodic table is a table that contains elements arranged in columns called groups and rows called periods.
Elements are arranged based on physical and chemical properties such that elements in the same group will have similar physical and chemical properties.

<h3>Chemical families </h3>

Based on the chemical properties elements belong to a family of elements sharing similar chemical or physical characteristics.
Examples of common chemical families include; alkali metals, alkaline-earth metals, halogens and noble gases among others.

<h3>Alkaline-earth metals </h3>

These are elements that are found in group 2 of the periodic table. Alkaline-earth metals include, Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium.

Properties of Alkaline-earth metals

Alkaline earth metals have a valence of two since they form ions by losing two electrons from their outermost energy levels.
Unlike the Alkali metals, the earth metals have a smaller atom size and are not as reactive compared to alkali metals.
Alkaline-earth metals are highly metallic and are good conductors of electricity.
They react with water and steam to form metal hydroxide and metal oxides respectively
They react with air to form metal oxides
Reactivity of alkaline metals depends on the ease of losing electrons, thus the reactivity increases down the group as the number of energy levels increases.
Additionally, alkaline-earth metals have low electronegativities and low electron affinities

Keywords: Chemical families, alkaline-earth metals, reactivity

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