Question

GOLD MEDEL AND FAN PLEASE 7 th grade work conecttions academy/

Answer 1

i know this is math but i could not find anyowne in the science section

Answer 2

Can you still help me, please?

Answer 3

ok

Answer 4

how do layers B and D compare in age if rock layers between B and D have eroded away, what is the bondary between B adn D called? http://assets.openstudy.com/updates/attachments/54355be3e4b09f2026eb5921-igreen45-1412783172647-sicencework.jpg

Answer 5

just 3 questions

Answer 6

Unconformity.

At some stage layer B was laid down, followed by layer C
Then erosion of the surface removed all of layer C at some location - perhaps sea level rose and wave action removed the top strata.

Later on layer D was laid down directly on top of layer B.

That can be ascertained by comparing the strata at adjacent sites where some of layers B, C & D are all present.

Answer 7

ok 2 more and we r done then i will give u a edle also fan u ;)

Answer 8

ok hit me

Answer 9

what is the half-life of strontimun-90 explain you answer https://www.connexus.com/content/media/920126-1142013-60430-PM-1598683706.jpg

Answer 10

Amount remaining = original amount * (1/2)^n ... where n is the number of half-lives

It doesn't say how much was released ... but the original amount is 100% = 1

so the amount remaining = 11% of 1 = 0.11

0.11 = 1 *(1/2)^n

0.11 = (1/2)^n


take logs to base 10 of both sides:

log 0.11 = n log 0.5

n = log 0.11 / log 0.5

n = 3.184

Each half-life is 32 years

So number of years taken = 3.184 half-lives x [32 years / half-life]

= 101.9 years

Answer 11

there, it took me a while but, there

Answer 12

wow 1 more :O

Answer 13

wait

Answer 14

im so sorry

Answer 15

what?

Answer 16

i was confused

Answer 17

Strontium-90 (90Sr) is a radioactive isotope of strontium produced by nuclear fission, with a half-life of 28.8 years.

Answer 18

ohh got it thanks

Answer 19

It undergoes decay into yttrium-90, with a decay energy of 0.546 MeV. Strontium-90 has applications in medicine and industry and is an isotope of concern in fallout from nuclear weapons and nuclear accidents.[1]

Answer 20

that was the first part

Answer 21

thats why theres a 1

Answer 22

Define the Geologic time scale and explin why geoglists use it to show earth's history (btw that is the last one)

Answer 23

Strontium-90 is a "bone seeker" that exhibits biochemical behavior similar to calcium, the next lighter group 2 element. After entering the organism, most often by ingestion with contaminated food or water, about 70–80% of the dose gets excreted. Virtually all remaining strontium-90 is deposited in bones and bone marrow, with the remaining 1% remaining in blood and soft tissues. Its presence in bones might possibly cause bone cancer, cancer of nearby tissues, and leukemia.

Answer 24

sorry about the ????

Answer 25

anymore??

Answer 26

its OK it happents alot to me 2

Answer 27

Define the Geologic time scale and explin why geoglists use it to show earth's history

Answer 28

yeah its a pain

Answer 29

The geologic time scale is used to group periods of time together that share a common geologic feature and/or biologic feature.

Answer 30

It is a very quick way for us to talk about a rock or sequence of rocks in a context that we readily understand, without having to specify a number or range of numbers.

Answer 31

wwo you're VERY GOOD

Answer 32

Here's kind of a silly example.

Answer 33

To geologists, the movie "Jurassic Park," would have referred to a period of time between about 150 - 200 million years ago. We know what was going on with rocks and such in the world at that time, and we also know what kinds of plants and animals were living in that time... and "Jurassic" made all of us geologists understand the same thing without length explanations.

Answer 34

just gave u a medle i'll fan ya now

Answer 35

This is a FUN fact to share

Answer 36

"Jurassic Park" was totally wrong!

Answer 37

Based on the dinosaurs that they showed, the movie should have been called "Cretaceous Park."

Answer 38

It's just a quick way for geologists to understand things, in a somewhat similar way that biologists classify organisms into groups - they can say something in one word, and all of the biologists who they're talking to will know what they mean without a long explanation.

Answer 39

Good links for you below. Easy to understand, if I've been confusing.

Answer 40

thank u for EVERYTHING AND THE TIME

Answer 41

http://en.wikipedia.org/wiki/Geologic_time_scale

Answer 42

i'm trying to fan u but it keeps loading

Answer 43

np igreen45

Answer 44

glad i could help

Answer 45

imma science junkie