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Kamila [148]
3 years ago
14

Give examples of the one element from the alkaline earth metal group and one from the noble gases group. Include each element at

omic number, atomic mass number of neutrons of valence electron number of electron shells and some common characterizes of elements from it group.
Physics
1 answer:
zhuklara [117]3 years ago
8 0
Alkali metals: left column of your periodic table (not hydrogen, but anything below it). They have one valence electron, which they are happy to share in a reaction.

Halogens: second column from the right of your periodic table. They are one electron short of a full shell, so they are reactive in the opposite way that alkalis are--they want electrons.

Atomic number (number of protons) is the big number on the periodic table square. Hydrogen's is 1.

Atomic mass is a little number down below. For example, Hydrogen's is 1.008.

Neutrons are a tricky subject, because different isotopes of the same element can have different numbers of neutrons. You can't generally get this from the atomic mass, because the atomic mass is a weighted average of naturally occurring isotopes. Hydrogen can have 0,1, or 2 neutrons. To answer this, you'd have to choose a particular isotope from the table of isotopes (a completely different chart from the periodic table) which has a certain number of neutrons: n = weight - Z.

Valence electrons are the electrons in the outermost shell. (The column of the table).

<span> Number of principal shells is the row of the periodic table. </span>
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A book falls off a shelf that is 10.0 m tall. What is the velocity at which the book hits the ground?
Elena L [17]

Answer:

14 m/s

Explanation:

The motion of the book is a free fall motion, so it is an uniformly accelerated motion with constant acceleration g=9.8 m/s^2 towards the ground. Therefore we can find the final velocity by using the equation:

v^2 = u^2 + 2gd

where

u = 0 is the initial speed

g = 9.8 m/s^2 is the acceleration

d = 10.0 m is the distance covered by the book

Substituting data, we find

v=\sqrt{0^2 + 2(9.8 m/s^2)(10.0 m)}=14 m/s

8 0
3 years ago
A rocket passes you at a speed of 0.85c, and you measure its length to be 35.0 m. What is its measured length when at rest?
viktelen [127]

Answer:

66.4 m

Explanation:

To solve the problem, we can use the length contraction formula, which states that the length observed in the reference frame moving with the object (the rocket) is given by

L=L_0 \sqrt{1-(\frac{v}{c})^2}

where

L_0 is the proper length (the length measured from an observer at rest)

v is the speed of the object (the rocket)

c is the speed of light

Here we know

v = 0.85c

L = 35.0 m

So we can re-arrange the equation to find the length of the rocket at rest:

L_0 = \frac{L}{\sqrt{1-(\frac{v}{c})^2}}=\frac{35.0}{\sqrt{1-(\frac{0.85c}{c})^2}}=66.4 m

8 0
3 years ago
The average period of pendulum clock is found to be 1.2s at sea level. The period of the same pendulum on a mountain top is foun
Kipish [7]

Answer:

g' = 10.12m/s^2

Explanation:

In order to calculate the acceleration due to gravity at the top of the mountain, you first calculate the length of the pendulum, by using the information about the period at the sea level.

You use the following formula:

T=2\pi \sqrt{\frac{l}{g}}         (1)

l: length of the pendulum = ?

g: acceleration due to gravity at sea level = 9.79m/s^2

T: period of the pendulum at sea level = 1.2s

You solve for l in the equation (1):

l=\frac{gT^2}{4\pi^2}\\\\l=\frac{(9.79m/s^2)(1.2s)^2}{4\pi^2}=0.35m

Next, you use the information about the length of the pendulum and the period at the top of the mountain, to calculate the acceleration due to gravity in such a place:

T'=2\pi \sqrt{\frac{l}{g'}}\\\\g'=\frac{4\pi^2l}{T'^2}

g': acceleration due to gravity at the top of the mountain

T': new period of the pendulum

g'=\frac{4\pi^2(0.35m)}{(1.18s)^2}=10.12\frac{m}{s^2}

The acceleration due to gravity at the top of the mountain is 10.12m/s^2

5 0
3 years ago
Is it possible for an object that has a constant negative acceleration to change the direction in which it is moving? Explain wh
lozanna [386]
Yes! I think there are two ways you could go with this answer: 1) Acceleration is the change in velocity over time, it can be negative or positive. If you have an object that is already moving forwards in a straight line and give it a constant negative acceleration, it will slow down and then start going in reverse. 2)Velocity is a vector, meaning it has both magnitude and direction. In the example above, the acceleration is due to a change in magnitude, or speed (from +ve to -ve) but not a change in direction. Something that has constant speed but is changing direction is also accelerating (like something that is orbiting). You could use the earth as an example, which is constantly accelerating due to moving in a circle around the sun. At any time in the year you can say that in half a year's time the earth's direction will be reversed.
4 0
3 years ago
According to the concept of length contraction, what happens to the length of an object as it approaches the speed of light and
lord [1]
When an object moves its length contracts in the direction of motion. The faster it moves the shorter it gets in the direction of motion.
The object in this question moves and then stops moving. So it's length first contracts and then expands to its original length when the motion stops.
The speed doesn't have to be anywhere near the speed of light. When the object moves its length contracts no matter how fast or slow it's moving.
8 0
3 years ago
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