Which of the following describes glass?

A scientist performs an experiment on an unknown element. She finds that the element forms an ionic bond with beryllium (Be) but

Bumek [7]

To fill up all of the valence electrons we must have 8 electrons total to have an ionic bond. In this case Lithium is in group 1 and so only has 1 valence electron and so it can bond with elements from group 17, since 7 + 1 = 8. However, this unknown element did bond with beryllium, and beryllium is in group 2 so it must bond with an atom that has 6 valence electrons. The elements that have 6 valence electrons are in group 16 not group 2. So the result does not support her conclusion.

4 0

3 years ago

Read 2 more answers

The diagram shows a wave moving from one medium to another

Shtirlitz [24]

As the speed of wave decreases, the wavelength of the wave decreases.

<h3>Refraction</h3>

We know that as a wave travels from one medium to another its speed decreases depending on if the first medium is less dense than the second medium or increases depending on if the first medium is more dense than the second medium. This is known as refraction

Now, we know that the speed of a wave v = fλ where

f = frequency and
λ = wavelength. Since f is constant, v ∝ λ.

The ratio of the speed in medium one to speed in medium two is called the refractive index of medium 1 to 2.

<h3>Explaining the diagram</h3>

From the diagram, we see that the wavelength in medium 1 is longer than that in medium 2. Since wavelength and speed are proportional, so the speed in medium 1 is also greater than the speed in medium 2.

So, As the speed of wave decreases, the wavelength of the wave decreases.

Learn more about refraction here:

brainly.com/question/25758484

3 0

2 years ago

A motorcycle daredevil plans to ride up a 2.0-m-high, 20° ramp, sail across a 10-m-wide pool filled with hungry crocodiles, and

il63 [147K]

Answer:

He becomes a croco-dile food

Explanation:

From the question we are told that

The height is h = 2.0 m

The angle is $\theta = 20^o$

The distance is $w = 10m$

The speed is $u = 11 m/s$

The coefficient of static friction is $\mu = 0.02$

At equilibrium the forces acting on the motorcycle are mathematically represented as

$ma = mgsin \theta + F_f$

where $F_f$ is the frictional force mathematically represented as

$F_f =\mu F_x =\mu mgcos \theta$

where $F_x$ is the horizontal component of the force

substituting into the equation

$ma = mgsin \theta + \mu mg cos \theta$

$ma =mg (sin \theta + \mu cos \theta )$

making a the subject of the formula

$a = g(sin \theta = \mu cos \theta )$

substituting values

$a = 9.8 (sin(20) + (0.02 ) cos (20 ))$

$= 3.54 m/s^2$

Applying " SOHCAHTOA" rule we mathematically evaluate that length of the ramp as

$sin \theta = \frac{h}{l}$

making $l$ the subject

$l = \frac{h}{sin \theta }$

substituting values

$l = \frac{2}{sin (20)}$

$l = 5.85m$

Apply Newton equation of motion we can mathematically evaluate the final velocity at the end of the ramp as

$v^2 =u^2 + 2 (-a)l$

The negative a means it is moving against gravity

substituting values

$v^2 = (11)^2 - 2(3.54) (5.85)$

$v= \sqrt{79.582}$

$= 8.92m/s$

The initial velocity at the beginning of the pool (end of ramp) is composed of two component which is

Initial velocity along the x-axis which is mathematically evaluated as

$v_x = vcos 20^o$

substituting values

$v_x = 8.92 * cos (20)$

$= 8.38 m/s$

Initial velocity along the y-axis which is mathematically evaluated as

$v_y = vsin\theta$

substituting values

$v_y = 8.90 sin (20)$

$= 3.05 m/s$

Now the motion through the pool in the vertical direction can mathematically modeled as

$y = y_o + u_yt + \frac{1}{2} a_y t^2$

where $y_o$ is the initial height,

$u_y$ is the initial velocity in the y-axis

$a_y$ is the initial acceleration in the y axis with a constant value of ( $g = 9.8 m/s^2$ )

at the y= 0 which is when the height above ground is zero

Substituting values

$0 = 2 + (3.05)t - 0.5 (9.8)t^2$

The negative sign is because the acceleration is moving against the motion

$-(4.9)t^2 + (2.79)t + 2m = 0$

Solving using quadratic formula

$\frac{-b \pm \sqrt{b^2 -4ac} }{2a}$

substituting values

$\frac{-3.05 \pm \sqrt{(3.05)^2 - 4(-4.9) * 2} }{2 *( -4.9)}$

$t = \frac{-3.05 + 6.9}{-9.8} \ or t = \frac{-3.05 - 6.9}{-9.8}$

$t = -0.39s \ or \ t = 1.02s$

since in this case time cannot be negative

$t = 1.02s$

At this time the position the motorcycle along the x-axis is mathematically evaluated as

$x = u_x t$

x $=8.38 *1.02$

$x =8.54m$

So from this value we can see that the motorcycle would not cross the pool as the position is less that the length of the pool

7 0

3 years ago

Why doesn't the north star move?<br><br>i need the answer asap and i will give brainliest

3241004551 [841]

☁️ Answer ☁️

annyeonghaseyo!

The answer is:

Because it takes the Earth a full year to move from one end of its orbit to the other, and because that distance is so tiny compared to the distance to the star, and because the star is aligned with the Earth's axis of rotation, it doesn't appear to ever move. The north pole coincidentally points at this star.

Hope it helps.

Have a nice day noona/hyung!~ ￣▽￣❤️

3 0

2 years ago

What kind of energy does a burning log have? Can't figure this out for homework. It just needs to be a short answer.

lina2011 [118]

I would assume thermal energy, since it's concerning heat and all. Although judging off of the fact that this is for physics, I don't think that would be the right answer in this case.

6 0

3 years ago

Which of the following describes glass?​

Which of the following describes glass?