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3 years ago

What causes light to refract?

1 answer:

8 0

on reflection from a smooth surface, the angle of the ... The reflected ray is always in the plane defined by the incident ray and the ... they reflect off a surface, move from one transparent medium into another, or travel ... be used to understand the images produced by plane and curved mirrors.

Light refracts whenever it travels at an angle into a substance with a different refractive index (optical density). This change of direction is caused by a change in speed. For example, when light travels from air into water, it slows down, causing it to continue to travel at a different angle or direction.

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A car starts from rest and accelerates uniformly at 2.0 m/s2 toward the north. A second car starts from rest 4.0 s later at the

yKpoI14uk [10]

Answer:

the correct solution is 13 s

Explanation:

This is a kinematic problem, let's use accelerated rectilinear motion relationships.

For the first car it has an accelerometer of 2.0 m/s²

x = v₀₁ t + ½ a₁ t²

The second car leaves the same point, but 4.0 seconds later

x = v₀₂ (t-4) + ½ a₂ (t-4)²

With this form we use the same time for both cars.

The initial speeds are zero for both vehicles leave the rest, at the point where they are located has the same position

x = ½ a₁ t²

x = ½ a₂ (t-4)²

Let's solve

a₁ t² = a₂ (t-4)²

a₁/a₂ t² = t² -2 4 t + 16

t² (1- 2.0 / 4.0) - 8 t +16

t² 0.5 - 8 t +16 = 0

t² -16 t + 32 = 0

Let's solve the second degree equation

t = [16 ±√( 16² - 4 32)] / 2

t = ½ (16 ± 11,3)

Solutions

t1 = 13.66 s

t2 = 2.34 s

These are the mathematical solutions for the meeting point, but car 2 leaves after 4 seconds, so the only solution is 13.66 s

the correct solution is 13 s, if you have to select one the nearest 12s

6 0

2 years ago

1. Which statement about subatomic particles is not true?

igomit [66]

1. Protons and neutrons have the same charge.

Protons have positive charge, equal to $e=+1.6\cdot 10^{-19} C$ , while neutrons have zero charge.

2. mass number

The mass number of an atom is equal to the sum of protons and neutrons inside its nucleus.

3. Atoms are made up of smaller particles.

According to Dalton's theory, atoms are the smallest particles that make matter, and they are indivisible and indestructible, so they are NOT made up of smaller particles.

4. a solid sphere

In Dalton's theory, atoms are not made of smaller particles, so we can think them as solid spheres.

5. J. J. Thomson

In his experiment with cathode ray tubes, JJ Thomson demonstrated the existance of the electrons, which are negatively charged particles inside the atom. In his model of the atom (plum-pudding model), Thomson thought the atom consists of a uniform positive charge and the electrons are located inside this positive charge.

6. An electron has the same amount of energy in all orbitals.

In fact, each orbital corresponds to a different energy level: the farther the orbital from the nucleus, the higher the energy of the electrons contained in that orbital.

7. A hydrogen atom in heavy water has an extra neutron.

Heavy water is a type of water that contains deuterium, which is an isotope of the hydrogen consisting of one proton and one neutron (so, one extra neutron).

8. The glowing beam was always deflected by charged plates

In his cathode's ray tube experiment, Thomson shows that the beam of unknown particles (= the electrons) were deflected by charge plates, so the particles had to be also electrically charged.

9. electrons move to a lower energy level

When electrons move from a higher energy level to a lower energy, they emit a photon (light) of energy equal to the difference in energy between the two energy levels.

10. orbital

In quantum mechanics, electrons in the atom are not precisely located, since we cannot determine their exact position and velocity at the same time. Therefore, we can only describe regions of space where the electrons have a certain probability to be found, and these regions of space are called orbitals.

11. 14

According to Dalton's theory, the proportions of the reactants must be respected in order to form the same compound. Therefore, we can write:

$2 g: 4 g = X : 28 g\\X=\frac{2 g \cdot 28 g}{4 g}=14 g$

12. negative charge, found outside the nucleus

Electrons are particles with negative charge of magnitude $e=-1.6\cdot 10^{-19}C$ that orbit around the nucleus. The nucleus, instead, consists of protons (positively charged, with charge opposite to the electron) and neutrons (neutrally charged).

13. move from higher to lower energy levels

When electrons move from a higher energy level to a lower energy inside a neon atom, they emit a photon (which is light) whose energy is equal to the difference in energy between the two energy levels.

14. atomic number from its mass number

In fact:

- the atomic number of an atom (Z) is equal to the number of protons inside the nucleus

- the mass number of an atom (A) is equal to the sum of protons+neutrons inside the nucleus

Therefore, we can find the number of neutrons in the nucleus by calculating the difference between A and Z:

Number of neutrons = A - Z

15. None of them

None of these examples is a good analogy to describe the location of an electron in an atomic orbital: in fact, the position of an electron in an orbital cannot be precisely described, we can only describe the probability to find the electron in a certain position, and none of these example is an analogy of this model.

8 0

2 years ago

What is the Sl unit for speed

Akimi4 [234]

Answer: meter per second

Explanation: meter per second

Speed has the dimensions of distance divided by time. The SI unit of speed is the meter per second, but the most common unit of speed in everyday usage is the kilometer per hour or, in the US and the UK, miles per hour. For air and marine travel the knot is commonly used.

3 0

3 years ago

Two ladybugs sit on a rotating disk that is slowing down at a constant rate. The ladybugs are at rest with respect to the surfac

d1i1m1o1n [39]

The two ladybugs have same rotational (angular) speed

Explanation:

The rotational (angular) speed of an object in circular motion is defined as:

$\omega=\frac{\theta}{t}$

where

$\theta$ is the angular displacement

t is the time interval considered

Here we have two ladybugs, which are located at two different distances from the axis. In particular, ladybug 1 is halfway between ladybug 2 and the axis of rotation. However, since they rotate together with the disk, and the disk is a rigid body, every point of the disk cover the same angle $\theta$ in the same time $t$ : this means that every point along the disk has the same angular speed, and therefore the two ladybugs also have the same angular speed.