# Solar radiation, mars, earths and equations help please?

• helpemz2011
In summary: S104 OUi don't know what you're talking about. I've been nothing but helpful, and I've provided no answers. I've only guided you towards the correct answers. Trust me, you'll be able to do these things yourself if you just stop overthinking it.You've come up with the right answer. That means you're doing okay. And you've made that progress yourself. I haven't provided any answers to you.The answer you came up with is in Watts. But you were given units in W/m² and m². You need to see how to combine those units to get the units you want. That's called dimensional analysis. It's an important
helpemz2011

## Homework Statement

Earth and Mars are both rocky planets, but Mars is half as far away again from the Sun as Earth, so radiation from the Sun is not as powerful at the surface of Mars as at the Earth’s surface.
Using the values in Table 2, calculate the amount of solar radiation intercepted by the surface of Mars. Give your answer in scientific notation, to the appropriate number of significant figures, and in the correct units.
Table 2 Values of solar constant (W m−2) and area facing the Sun (m2) for Mars.
Mars
Solar constant (W m−2)
5.20 × 102
Area facing the Sun (m2)
3.6 × 1013

## The Attempt at a Solution

5.20x10(p-o)2 / 3.6x10(p-o)13 = 1.444444444x10(p-o)15 -

1.4x10(p-o)15 W m

Can anyone tell me what i am doing wrong if my answer is wrong (which i am sure it is)

Cheers emz

Your result should be in watts (total amount of solar radiation incident on the surface of Mars). Look at the units of what you're given, and see what relationship will produce the desired resulting units.

To be honest i really don't know sorry i am really stuck. Are my calculations on the right track?

emz

No. You've got problems with the units. You need to understand how units combine when you do the math. They will guide you to the correct way to solve problems like this.

You are given the solar constant at Mars in W/m2, and the surface area catching the radiation in m2. You want a result in watts. How do you combine the given information?

Joules?

Divide the area facing the sun by the solar constant?

6.9x10(p-o)14 W

?

helpemz2011 said:
Earth and Mars are both rocky planets, but Mars is half as far away again from the Sun as Earth, so radiation from the Sun is not as powerful at the surface of Mars as at the Earth’s surface.

helpemz2011 said:
Joules?

Watts. You want watts. That's energy per unit time (Joules per second).

helpemz2011 said:
Divide the area facing the sun by the solar constant?

Let's see how those units work out:

$$\frac{[m^2]}{[W/m^2]} = \;??$$

What does that yield?

dacruick said:

Yeah that's what is in the question.

and W?

I just don't know I might just give up on this question sorry

Emz

I'm going to bridge dimensional analysis with our good old friend apples.

You have baskets which hold 30 apples each. The units are apples/basket.
You have 12 baskets, how many apples do you have?

Now you have 30 Watts/metre². How many Watts are incident on a sphere with a radius of 100 metres? Its the same process.

You seem to be flustered because you are overestimating the problem and underestimating your abilities. Also, Mars is not half the distance from the sun than the Earth.

dacruick said:
"Earth and Mars are both rocky planets, but Mars is half as far away again from the Sun as Earth, so radiation from the Sun is not as powerful at the surface of Mars as at the Earth’s surface."

Earth is at 1AU, Mars at about 1.5AU (okay, 1.523AU to be picky). So sure, the statement's okay.

Last edited:
ha solar constant x area facing the sun!

so 5.20x10(p-o)2 x 3.6x10(p-o)13 = 1.872x10(p-o)16

to appropriate significant figures -1.9x10(p-o)16 W

Bravo!

By the way, you can use the x2 and x2 buttons on the edit page to produce "real" superscripts and subscripts.

cheers its a pain in the backside writing (p-o) all the time thank you both x

helpmz2011
You may not post any of the TMA questions from The Open University on a public forum. This is considered to be cheating.

Oi!

Stop cheating!

EW - S104 OU

helpemz2011

If you read the textbook for S104 that you got you will find the method to do all the calculations you have asked about.

It is against the rules to post TMA questions to public forums and I suggest you di8scuss this within your tutor group forum in future.

EW

## 1. What is solar radiation?

Solar radiation is a form of energy that is emitted by the sun and travels through space to reach the Earth. It is made up of various types of electromagnetic radiation, including visible light, ultraviolet light, and infrared radiation.

## 2. How does solar radiation affect Mars?

Solar radiation plays a crucial role in the Martian climate and atmosphere. Due to Mars' thin atmosphere, the planet receives less solar radiation than Earth, resulting in colder temperatures and less heat retention. However, solar radiation is also responsible for driving weather patterns on Mars and is essential for sustaining any potential life on the planet.

## 3. What is the difference between solar radiation on Earth and Mars?

The main difference between solar radiation on Earth and Mars is the amount received. Earth's atmosphere and magnetic field help to protect it from harmful radiation, resulting in a higher amount of solar energy reaching the surface. On Mars, there is a thinner atmosphere and no magnetic field, meaning less solar radiation reaches the surface.

## 4. How can equations help understand solar radiation on Mars and Earth?

Equations can help scientists better understand the relationship between solar radiation and various factors, such as the distance from the sun, atmospheric conditions, and the amount of radiation absorbed or reflected. By using equations, scientists can make predictions and calculations to better understand the effects of solar radiation on Mars and Earth.

## 5. How does solar radiation impact life on Earth?

Solar radiation is essential for sustaining life on Earth. It provides energy for photosynthesis, which is the process by which plants produce oxygen and food. Solar radiation also plays a role in regulating the Earth's climate and weather patterns, making it crucial for maintaining a habitable environment for living organisms.

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