Questions in the Science & Nature category.
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March 10

Help me size an LED driver--I'm confused.

I'd like to build a shop light/tinker light out of cheap LED COBs, but I'm confused about how to size the driver. COBs have wattage, voltage and amperage ratings. To my understanding, to run 3 10w COBs, I would need a driver that puts out 30 watts. The voltage seems pretty straight forward, it's represented by a single number and the driver should be capable of delivering that. The amperage is where I get REALLY confused. [more inside]
posted by OmieWise at 12:24 PM - 3 answers

March 7

Gardening question: should I remove lawn from around a young tree?

After much lobbying, the council has planted some trees on the London housing estate where I live. Three years on, some are doing well, others less so. Some have been planted in grass-covered areas, and the grass has regrown up to the trunks. Could this be a major factor in why they're not growing very well? Is it likely to make much of a difference if I remove the grass around the base of the tree? Do I risk damaging the roots if I do?
posted by snarfois at 2:39 AM - 6 answers

March 5

How to calculate uncertainty when redistributing a population

I am trying to understand a statistical problem with resampling and variation, and I’m unsure of my terminology so it’s hard to search. I have a set of geographic areas with known populations, and I’d like to generate new areas with redistributions of those populations. I can assume that the population is evenly spread throughout the original areas, but this gives me numbers without any kind of confidence interval. What would I need to do to calculate variance or deviation for this problem? [more inside]
posted by migurski at 5:02 PM - 10 answers

How To Preserve a Beetle

How do you preserve a dead beetle for long lasting ornamental value? [more inside]
posted by glitter at 4:51 PM - 4 answers

March 3

Science, please

Is there any scientific evidence that PMS/hormones make women unreliable/unstable? [more inside]
posted by yawper at 7:01 AM - 17 answers

March 1

Can I be hypnotized?

I lost/hid/misplaced an expensive and sentimental piece of jewelry several months ago. I really think I hid it somewhere in my house but I've searched and searched with no luck. Is hypnosis to remember what I did with it a real thing? Maybe I just lost it outside the house. I know it was in my purse at one point. [more inside]
posted by tamitang at 7:19 PM - 8 answers

Tools & sites for Junior Rock Hounds in New England?

What things should I bring along on a hike with some kids (age 9 & 12) who are curious about looking for cool rocks after a great demo in school? [more inside]
posted by wenestvedt at 1:40 PM - 7 answers

February 26

Non-technical book about neural networks?

Is there a non-technical book that explains neural networks in sort of an introductory way for general readers? [more inside]
posted by Dr. Send at 8:36 AM - 12 answers

February 25

What are these ants doing?

Please explain this ant (and other small insect) behavior I'm witnessing. [more inside]
posted by BlahLaLa at 11:45 AM - 6 answers

February 24

What is the scientific principle that governs how big animals get?

After seeing the trailer for the latest King Kong movie, it got me thinking about why animals only get as big as they do. Is it because they evolve in an ecosystem and natural selection doesn't want you getting bigger than the food supply can managably feed? Is there a scientific principle that governs this that people have named? Is it a DNA thing? I guess I'm wondering what prevents gorillas from growing 100 feet tall. Could there ever be a mutation that allows this to happen? Thanks!
posted by Sully at 3:03 PM - 13 answers

February 22

How do chemical reactions in the brain create feelings?

Dopamine floating around in your synapses will make you feel g<ood. But how? [more inside]
posted by marvelousmellitus at 8:32 PM - 17 answers

Buoyancy question

i want to put an inflatable pool in my small backyard. Then I want to fill it with water and lie on its surface on an inflatable chaise/raft thing. [more inside]
posted by DMelanogaster at 2:33 PM - 10 answers

February 20

Research/articles/books on play in school-aged children

I am looking for research/articles/books on play in school-aged children. Ideally, about cooperative, imaginative play. I have found lots about play development from infancy to preschool age, but what I'm looking for is ages 5-13. Who has studied this period?
posted by xo at 5:33 PM - 8 answers

What are these clear, nubbly, podlike things that I found on the beach?

On January 28, at Schoolhouse Beach in Bodega Bay, California, I found scores and scores of these odd little things washed up on the beach. Do you know what they are? [more inside]
posted by Dr. Wu at 4:04 PM - 8 answers

February 19

What Animal Skull Is This?

These are some pictures of the skull. The skull is from western Montana, which includes prairies. It was given to a friend of mine. It is about six to seven inches across and about 8-9 inches long. [more inside]
posted by ITravelMontana at 7:35 PM - 13 answers

February 18

What's this flowering plant called?

What's this flowering plant called? It's short, has thin grass-like leaves, and seems to pop up every spring in the middle of Alabama (Zone 8a).
posted by gregr at 1:51 PM - 13 answers

February 17

Can using a ipod on a louder volume drain the battery quicker.

Was thinking if I listen to my Ipod louder will it drain the battery quicker than if I listen to it at a quiter volume? However, I'm just using an Ipod as an example. I guess the same could be asked of any electrical item; say a TV set will it use more power if watched at a louder volume.
posted by maxmix at 9:55 AM - 11 answers

February 14

When will the Sun shine on Sunshine?

My four story apartment building is about 15 feet from a nearly identical four story apartment building to the south. I live on the third floor, and my apartment windows face south into the space between the buildings. Today at midday I can see the sun shining fully on the windows of the fourth floor apartment above mine, with the shadow from the other building starting just below their windows. How many days until it starts shining into my apartment and onto my cat? [more inside]
posted by carsonb at 12:18 PM - 7 answers

February 13

Fish out of water

Can fish see through air? If you take a fish out of the water, can it resolve images and see as clearly as it presumably does in water? Or does its sight go all blurry the way mine does underwater?
posted by tavegyl at 11:56 PM - 3 answers

February 12

Why aren't seasons different lengths? Or are they?

Because the earth has an elliptical orbit, it travels at different speeds depending how far it is from the sun. Does this make some seasons longer than others? If not, why not? [more inside]
posted by Literaryhero at 6:27 PM - 9 answers

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