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4 years ago

5

_____ prescribed atoms as having a positive nucleus with electrons that have different energies at different distances from the

nucleus

1 answer:

galina1969 [7]4 years ago

3 0

Answer

Niels Bohr

Explanation

in 1915, Niel Bohr proposed a model of the atom which is known as Bohr Model of atoms. Bohr modified the Rutherford Model of atom and some people called this model as Rutherford-Bohr Model. Bohr model was based on quantum mechanics.

The Bohr Model was similar to planetary model. According to Bohr, electrons which are negatively charged are present in an orbit around the positively charged nucleus in a similar manner like planets revolves around the Sun in an orbit. .

main postulates of Bohr's model are as follows

Electrons are present around the nucleus in orbits which have a set size and energy.
Energy of the orbit in which electrons are present depends on the size of the orbit. smallest orbit has the lowest energy.
When transition of an electron takes place (when electron moves from one orbit to another orbit) that time energy (radiation) is emitted or absorbed.

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Write in powers of 10 notation: 3 trillion; five-thousandths; 730,000,000,000,000; 0.000000000082.

Leno4ka [110]

3 trillion= 3X10^<span>12
5 thousanths= 5X10^-3
730000000000000= 7.3X10^14
0.000000000082= 8.2X10^-11</span>

5 0

3 years ago

A worker exerts a pulling force on a box. The worker exerts this force by attaching a rope to the box and pulling on the rope so

shusha [124]

Answer:

<em>The magnitude of the pulling force is 20.66% of the gravitational force acting on the box</em>

Explanation:

<u>Accelerated Motion</u>

The net force exerted on a body is the (vector) sum of all forces applied to the body. The net force can be decomposed in its rectangular components and the dynamics of the body can be studied in each direction x,y separately.

Let's start off by calculating the acceleration the worker gives to the box when pulling it. The distance traveled by the box initially at rest in a time t at an acceleration a is given by

$\displaystyle x=\frac{at^2}{2}$

Solving for a

$\displaystyle a=\frac{2x}{t^2}$

$\displaystyle a=\frac{2\cdot 10}{5.12^2}$

$a=0.763\ m/s^2$

Now we analyze the geometric of the forces applied to the box. Please refer to the free body diagram provided below.

The forces in the y-axis must be in equilibrium since no movement takes place there, thus, being g the acceleration of gravity:

$T_y+N=m.g$

There Ty is the vertical component of the tension of the rope, N is the normal force, and m is the mass of the box

The decomposition of T gives us

$T_y=Tsin\theta$

$T_x=Tcos\theta$

Solving the above equation for N

$Tsin\theta+N=m.g$

$N=m.g-Tsin\theta\text{..........[1]}$

Now for the x-axis, there are two forces acting on the box, the x-component of the tension and the friction force Fr. Those forces are not equilibrated, thus acceleration is produced:

$Tcos\theta-F_r=m.a$

Recalling that

$F_r=\mu N$

$Tcos\theta-\mu N=m.a$

Replacing N from [1]

$Tcos\theta-\mu (m.g-Tsin\theta)=m.a$

Operating

$Tcos\theta-\mu m.g+\mu Tsin\theta=m.a$

Solving for T

$T(cos\theta+\mu sin\theta)=m.a+\mu m.g$

$\displaystyle T=\frac{m.a+\mu m.g}{cos\theta+\mu sin\theta}$

$\displaystyle T=m\frac{a+\mu g}{cos\theta+\mu sin\theta}$

We don't know the value of m, thus we'll plug in the rest of the data

$\displaystyle T=m\frac{0.763+0.10\cdot 9.8}{cos36.8^o+0.10 sin36.8^o}$

$T=2.0252m$

Dividing by the weight of the box m.g

$T/(m.g)=2.0252/9.8=0.2066$

Thus, the magnitude of the pulling force is 20.66% of the gravitational force acting on the box

7 0

3 years ago

Which lists imaging techniques that use wave behaviors in order of increased risk of cancer from least risk to greatest

Cerrena [4.2K]

Imaging techniques that use wave behaviors are -

sonography
X-ray radiography
CT scan

<h3>How can mechanical waves help in the treatment of cancer?</h3>

Ultrasound is used to improve absorption of a radioactive pellet by a tumor. The radioisotope in a radiopharmaceutical releases sound waves into surrounding cells. Beams of X-rays are targeted at a cancerous tumor from outside the body.

<h3>How can mechanical waves help the treatment of cancer?</h3>

HIFU is a cancer treatment that uses high-frequency sound waves. You have HIFU from a machine. The machine gives off the sound waves which deliver a strong beam to a specific part of a cancer. This heats and destroys the cancer cells.

HIFU can treat a single tumour or part of a large tumour. But it is not suitable for people with cancer that has spread to more than one place in their body.

To learn more about cancer from the given link

brainly.com/question/11710623

#SPJ4

7 0

2 years ago

The force of attraction between a positive ion and a negative ion in an ionic<br> compound

Crazy boy [7]

Force of attraction between one atom and another within a compound formed by sharing of electrons or the loss and gain of electrons this is a bond

3 0

3 years ago

The formula for calculating work is ___.

Orlov [11]

Hey!

Formula for calculating work = Force × distance
Work done = Force applied on the object × distance travelled by it.

Hope it helps...!!!

3 0

4 years ago