What are the two types of opportunity cost? Select two.

A roller coaster pushes a 25 kg person upward with a force of 300 N. What is the acceleration?

vlada-n [284]

300N/25 kg= divide them for the answer

8 0

3 years ago

Can you please answer these ASAP!

SVEN [57.7K]

Answer:

Let's explain this briefly.

Suppose that we have a piece of ice (this is, solid water) now we give energy to the piece of ice, so the temperature of the ice increases. There is a point where the piece of ice will start a change of phase, at this point the temperature of the ice stops increasing because all the energy we give to the ice is used in the change of phase.

Once we have a complete change of phase, the temperature can increase again, and now we will have liquid water.

If we keep increasing the temperature we will see this happen again, when we have the transition from liquid to gas.

(and a similar thing happen when we have a material in a given phase and we remove heat from the material).

In the images we can see the different changes of phase of water.

1) In the first image we can see the circle in a part where the temperature is constant, so the temperature does not change in this part, which means that there is a change of phase happening.

2) Here we have the circle in a diagonal line, so here the temperature is changing, meaning that we have an increase of temperature in this region.

3) Here we want to know what the x-axis represents, this should rerpesent the energy that is being given to the material (so in some parts we see that the temperature increases and in other parts we see that the material changes of phase)

Then here the correct option is heat over time.

4) The freezing point is the temperature in which the change of phase from liquid to solid happens (or solid to liquid).

In the graph we can see that this change of phase happens at the temperature T = -210°C

Then the correct option is -210°C (The last option)

4 0

3 years ago

Imagine you’re driving along a road and you approach a bridge. You notice a sign that reads, “Bridge freezes before road.” Why d

nydimaria [60]

<u>Answer:</u>

<h3>During wet and freezing temperatures, ice is able to form at a faster pace on bridges because freezing winds blow from above and below and both sides of the bridge, causing heat to quickly escape. The road freezes slower because it is merely losing heat through its surface.</h3>

<u>Sources:</u>

-- https://intblog.onspot.com/en-us/why-do-bridges-become-icy-before-roads

and

-- https://www.accuweather.com/en/accuweather-ready/why-bridges-freeze-before-roads/687262

I hope this helps you! ^^

6 0

3 years ago

A garrafa térmica (também conhecida como "vaso de Dewar") é um dispositivo extremamente útil para conservar, no seu interior, co

igor_vitrenko [27]

Answer:

A opção A está correta.

O sistema formado pela garrafa térmica e a água perde 400 cal de calor para o meio ambiente.

Option A is correct.

The system formed by the thermos and the water loses 400 cal of heat to the environment.

Explanation:

Quando a temperatura de um sistema reduz, fica claro que o sistema perdeu calor ou energia térmica. Como a temperatura é um dos indicadores mais claros disso, esta conclusão é hermética e correta.

Mas, para saber a quantidade de calor perdida para o meio ambiente, agora fazemos alguns cálculos de energia térmica.

Transferência de calor de ou para o sistema de água e garrafa térmica = c × ΔT

c = capacidade térmica do sistema de água e garrafa térmica = 80 cal /°C

ΔT = Alteração da temperatura do sistema de água e garrafa térmica = (temperatura final) - (temperatura inicial) = 55 - 60 = -5°C

Calor transferido = 80 × -5 = -400 cal.

O sinal de menos mostra que o calor é transferido para fora do sistema, ou seja, o calor é perdido no sistema.

Espero que isto ajude!!!

English Translation

The thermos (also known as "Dewar vase") is an extremely useful device to conserve bodies (essentially liquid) at high temperatures, minimizing energy exchanges with the environment, which is generally colder. A thermos contains water at 60 o C. The thermos + water set has a thermal capacity of C = 80 cal / o C. The system is placed on a table and, after a considerable period of time, its temperature decreases to 55 o C. In this case, it is concluded that the system formed by the thermos and the water inside:

a) lost 400 cal. B) gained 404cal. C) lost 4 850 cal. D) gained 4 850 cal. E) did not exchange heat with the external environment.

Solution

When a system's temperature reduces, it is clear to conclude that the system has lost heat or thermal energy. Since temperature is one of clearest indicators of this, this conclusion is airtight and correct.

But, to know the amount of heat lost to the environment, we now do some thermal energy calculations.

Heat transferrred from or to the water and thermos system = c × ΔT

c = heat capacity of the water and thermos system = 80 cal/°C

ΔT = Change in temperature of the water and thermos system = (final temperature) - (initial temperature)

= 55 - 60 = -5°C

Heat transferred = 80 × -5 = -400 cal.

The minus sign shows that the heat is transferred out of the system, that is, the heat is lost from the system.

Hope this Helps!!!

7 0

3 years ago

We can detect 21-cm emission from other galaxies as well as from our own Galaxy. However, 21-cm emission from our own Galaxy fil

amid [387]

Answer:

Explanation:

Galaxies are in constant motion with respect to each other . For example Andromeda galaxy is approaching our galaxy ( milky way ) at about 110 km /s . So we will observe blue shift in the spectrum of radiation coming from this galaxy . In this way, we can distinguish between radiation coming from our galaxy and that coming from other galaxy . Spectrum of radiation coming from other galaxy must have either red or blue shift .

6 0

3 years ago