All Answers

jnjnxdsd:
The annual production of rice is
32,000,000,000,000 Kg. How many years
would it take to grow a mole or rice grains?
mole = 602 000 000 000 000 000 000 000

A mole of rice grains = 6.02 x 10 ²³
There is an average of about 36,590 grains of rice in a Kg

So a mole of rice grains must weigh
(6.02 x 10 ²³) / 36590 = 1.6453 x 10 ¹⁹ Kg

Annual production = 3.2 x 10 ¹³

Number of years = (1.6453 x 10 ¹⁹) / (3.2 x 10 ¹³) = > about 515,406 years.

MelodyJan 15, 2014

+118725

anon:
25 to the power of -1/2

Whenever anything is raised to a negative power it is the same a the reciprocal being raised to a positive power.
so
25 to the power of -1/2 = 1 / (25 to the power of +1/2)

A power of a half is the same as a sqrt so this equals 1 / (sqrt25)

I am sure that you can finish it yourself

MelodyJan 15, 2014

0.245 is smaller than 0.5 . first to check and see which decimal is bigger, you have to have common decimal places. that means that if there is 3 numbers behind a decimal in one number, than there has to have 3 numbers behind the decimal in the second number. so put two zeros behind the 0.5 so it becomes 0.500 . then compare them. is 0.245 or 0.500 bigger? so act like the zero and decimal arent there. is 245 or 500 bigger?

GuestJan 15, 2014

Speed of light in Air and in vacuum are considered to be the same 3*(10^8) m/s = c

no complicated answer here. I got the relative time would be the same 60 s, but I expect to be wrong unless proven otherwise.

GuestJan 15, 2014

+118725

???:
:( Help!
ms.blanco lives 7 blocks from a school and 4 blocks from from the nearest coffee shop. calculate the possible distances from the school to the shop.

The question is not comprehensive. (It is slightly open to different interpretations)
but
I'll give you the short answer. Draw a picture to see what I mean.

If you have to walk past the coffee shop to get to school then they will be 7-4 = 3 blocks apart.
The they are in opposite directions from the house then they will be 4+7 = 11 blocks apart.

If you take a block as a unit of distance then they can be anything from 3 to 11 blocks apart.

It really depends upon what you actually mean by 'block'.
and on whether you are talking road distance or air distance.

MelodyJan 15, 2014

Jan 14, 2014

+118725

WalterPeculier:
If it took light 60 seconds to travel 1 meter, how many times would time be slower than normal?

If you tell us what the normal 'air' speed is, that would help. (preferably in m/s)
I am sure you could get an answer easily if you google it.

MelodyJan 14, 2014

If the light slows because of relativistic processes then time is slowed by a factor of 17987547221. About 571 years to 1 second.
Light slows for others reasons: Passing through water it slows by a factor of 1.3 compared to a vacuum.

GuestJan 14, 2014

+118725

coolkid89:
3x-5y=3

This is not a question. It is the equation of a line.

MelodyJan 14, 2014

+118725

Prisca:
f(x)=1/2x-6 find x such that f(x) is not defined

For starters, this is your actual function
f(x)=1/2x-6
f(x)=(1/2)*x-6
f(x)=x/2 -6
and this function is a line that is defined for all x

I think the function that you really want is
f(x)=1/(2x) -6

Now, 2x is the denominator of the fraction. (what you are dividing by)
what can you not divide by? There is only one number that you can't divide by because it makes no sense.
If you can answer that question then you will know what x cannot be

MelodyJan 14, 2014

please i need it for hw tonight!

GuestJan 14, 2014

+118725

Lisa:
I need to calculate the amount of earths that would be required if everyone in the world had the same ecological footprint as me. The current world population is roughly 7, 140, 481, 761. My ecological footprint is 21. acres and there is only 28.2 billion acres of productive land and ocean available on earth. Help please. I need to know the calculations used as well.

Lisa

When there are big numbers in a question that look scary, just swap them for little numbers and see what you would do. Then do the same on the big numbers.
I'll show you what i mean.
Think about your question
The current world population is roughly 7, 140, 481, 761. My ecological footprint is 21. acres. What is the human population's footprint?
a similar question (though not a real one) could be
The current world population is roughly 10 My ecological footprint is 2 acres. What is the human population's footprint? 2acres each, 10people = 2 x 10 acres.
Now use the same the same logic to answer your 'real' question.

If you want to compare your answer to the 28.2 billion acres of productive land and ocean available, there is another little problem.
In Australia and the UK I think, 1 billion is 1million million = 1,000,000,000,000 = 10 ¹²
In the US 1 billion is 1thousand million = 1,000,000,000 = 10 ⁹

These sorts of discrepancies is one reason why it is better to use scientific notation when talking about big (or tiny) values.

MelodyJan 14, 2014

+118725

Keke:
The New Horizon Spacecraft began its 3.5 X 10^9-mile journey to Pluto in January 2006. If the cost of this mission is$0.20 per mile, find the total cost.

Just multiply the 2 numbers together.

MelodyJan 14, 2014

GuestJan 14, 2014

+118725