A substance can absorb heat energy by the process of

Help with these please someone

Mice21 [21]

Answer:

Five: B

Ten: A

Explanation:

Five

An alpha decay looks like this.

$A^x_y====> B^{x-4}_{y - 2}+alpha^4_2$

So whatever is produced must have a mass of 4 less than 234 and a number on the periodic table of 2 less than 92. In other words, B has a mass of 230 and a number on the periodic table of 90.

The answer should be Thorium which is B.

Ten

There is actually not enough information to do 10. You get it by making an assumption and seeing if it works.

In general a beta decay can (the most common one ) look like this.

$A^x_y====> B^{x}_{y-1}+Beta^0_{-1}$

Is there anything that looks like that?

The weight stays the same (234) and the atomic number of the mother element (on the left) is 1 lower than the given chemical on the right.

$Th^{234}_{90}====> Pa^{234}_{91}+Beta^0_{-1}$

The answer is Thorium A

Beta decays are very tricky. Be very careful how you handle them. One of three items can be what is decayed. I have assumed it was an electron, but there are two other possibilities. I won't confuse you by adding them. Just be aware that they exist.

3 0

3 years ago

a stone is thrown vertically upwards with a velocity of 20 m per second determine the total time of flight of stone in air

miv72 [106K]

Answer:

Explanation:

The best way to do this is to remember the rule about the halfway mark in a parabolic path. At a trajectory's half way point in its travels, it will be at its max height. To get the total time in the air, we take that time at half way and double it. Here's what we know that we are told:

initial velocity is 20 m/s

Here's what we know that we are NOT told:

a = -9.8 m/s/s and

final velocity is 0 at an object's max height in parabolic motion.

We will use the equation:

$v=v_0+at$ where v is final velocity and v0 is initial velocity. Filling in:

0 = 20 + (-9.8)t and

-20 = -9.8t so

t = 2 seconds. The stone reaches its max height 2 seconds after it is thrown; that means that after another 2 seconds it will be on the ground. Total air time is 4 seconds.

8 0

3 years ago

In a particular experiment to study the photoelectric effect, the frequency of the incident light and the temperature of the met

Molodets [167]

Answer:

The number of electrons emitted from the metal per second increases.

Explanation:

The photoelectric effect can be explained by thinking the incident light as made of many photons, each carrying an energy of

$E=hf$

where h is the Planck constant and f is the light frequency. A photoelectron is extracted from the metal if the energy of the incoming photon, which hits the electron and gives all its energy, is at least equal to the work function of the metal, $\phi$ . Moreover, each photon of the incident light hits only one electron in the metal.

Given these premises, we can analyze each statement:

The work function of the metal decreases. --> FALSE. The work function is just the energy needed to extract photoelectrons from the metal: so, it depends only on the properties of the metal, and not on the intensity of the incident light.

The number of electrons emitted from the metal per second increases. --> TRUE. The intensity of the incident light is proportional to the number of photons contained in the light: so, the higher the intensity, the larger the number of photons that hit the electrons in the metal, the larger the number of electrons emitted.

The maximum speed of the emitted electrons increases. --> FALSE. The energy of the electrons emitted depends ONLY on the energy of the incoming photon, so it depends only on the frequency of the photon, not on the number of photon (intensity). In fact, only 1 photon at time hits 1 electron, so the intensity of the light does not affect the energy of the electrons (and so, it does not affect their speed)

The stopping potential increases. --> FALSE. The stopping potential is the potential needed to stop the electrons in the metal preventing them to escape the metal: this depends only on the energy of the electron, which does not depend on the intensity of the light, but only on its frequency.

4 0

3 years ago

What are fossil fuels composed of? 1.Carbon 2.Nitrogen 3.Oxygen

Monica [59]

Answer:

fossil fuels are composed of Carbon.

5 0

3 years ago

Read 2 more answers

Two unknown resistors are connected together. When they are connected in series their equivalent resistance is 15 Ω. When they a

DochEvi [55]

Explanation:

Let x and y are two unknown resistors. When they are connected in series their equivalent resistance is 15 Ω. When they are connected in parallel, their equivalent resistance is 3.3 Ω.

For series combination,

$x+y=15$ ......(1)

For parallel combination,

$\dfrac{1}{x}+\dfrac{1}{y}=3.3$ ....(2)

We need to find the resistances of these resistors. Solving equation (1) and (2) we get :

x = 0.29 and y = 14.7

Hence, the resistances of these resistors are 0.29 ohms and 14.7 ohms.

6 0

3 years ago