Things you always wanted to know the answer to [Vol. 3]

Things you always wanted to know the answer to [Vol. 3]

TOPIC CLOSED
TOPIC CLOSED
Author
Discussion

Issi

1,782 posts

150 months

Friday 5th June 2015
quotequote all
Why are the majority,( or so it seems), of the riders in the IoM TT from the North of England?

Is road racing a much bigger deal in the North than it is in the South?

walm

10,609 posts

202 months

Friday 5th June 2015
quotequote all
TwigtheWonderkid said:
No moon, no tides, no currents, no flow of seas, no oxygenation of the sea, no life in the sea, no life on Earth, or not as we know it. Plus without the moon we'd have a different orbit of the sun so different conditions.
Wind can cause currents.
And I am pretty sure that oxygenation happens at the surface mostly (you know, at the air/water interface.)
The sea would still have a surface!!!!

The med is hardly tidal at all and manages to sustain plenty of life.

Timmy40

12,915 posts

198 months

Friday 5th June 2015
quotequote all
I found out a very good answer to something, to work out how long a battery will power an electrical device for you multiply the AH by 10 then divide that by the wattage of the device, and the result is how many hours you can run the device for.

walm

10,609 posts

202 months

Friday 5th June 2015
quotequote all
Timmy40 said:
I found out a very good answer to something, to work out how long a battery will power an electrical device for you multiply the AH by 10 then divide that by the wattage of the device, and the result is how many hours you can run the device for.
Just - no.

1kW kettle attached to a 1,000Ah battery.

10 hours according to your math.

Completely ignoring the voltage of the battery which of course determines how much power is actually stored in the batttery.

Timmy40

12,915 posts

198 months

Friday 5th June 2015
quotequote all
walm said:
Timmy40 said:
I found out a very good answer to something, to work out how long a battery will power an electrical device for you multiply the AH by 10 then divide that by the wattage of the device, and the result is how many hours you can run the device for.
Just - no.

1kW kettle attached to a 1,000Ah battery.

10 hours according to your math.

Completely ignoring the voltage of the battery which of course determines how much power is actually stored in the batttery.
The 10 is used as an approximation for 12 ( as in 12V ), allowing some margin for not having a 100% efficient inverter.

walm

10,609 posts

202 months

Friday 5th June 2015
quotequote all
Timmy40 said:
walm said:
Timmy40 said:
I found out a very good answer to something, to work out how long a battery will power an electrical device for you multiply the AH by 10 then divide that by the wattage of the device, and the result is how many hours you can run the device for.
Just - no.

1kW kettle attached to a 1,000Ah battery.

10 hours according to your math.

Completely ignoring the voltage of the battery which of course determines how much power is actually stored in the batttery.
The 10 is used as an approximation for 12 ( as in 12V ), allowing some margin for not having a 100% efficient inverter.
Right.
And if I have a 24v battery? Or 1.5v?

Timmy40

12,915 posts

198 months

Friday 5th June 2015
quotequote all
walm said:
Timmy40 said:
walm said:
Timmy40 said:
I found out a very good answer to something, to work out how long a battery will power an electrical device for you multiply the AH by 10 then divide that by the wattage of the device, and the result is how many hours you can run the device for.
Just - no.

1kW kettle attached to a 1,000Ah battery.

10 hours according to your math.

Completely ignoring the voltage of the battery which of course determines how much power is actually stored in the batttery.
The 10 is used as an approximation for 12 ( as in 12V ), allowing some margin for not having a 100% efficient inverter.
Right.
And if I have a 24v battery? Or 1.5v?
Then for a 24V battery assuming you have a suitable inverter I assume it's 24 * the AH divided by the wattage. To be honest I've only see 12V inverters to allow a 3 pin plugged device to run off a car batter anyway. Which is what most people would want to do.

walm

10,609 posts

202 months

Friday 5th June 2015
quotequote all
Timmy40 said:
Then for a 24V battery assuming you have a suitable inverter I assume it's 24 * the AH divided by the wattage. To be honest I've only see 12V inverters to allow a 3 pin plugged device to run off a car batter anyway. Which is what most people would want to do.
OK - perhaps I jumped the gun.
Your rule of thumb will clearly work well for the most common use.

I don't know the wattage of my smoke detectors anyway and those duracells didn't have an Ah rating after all!

Timmy40

12,915 posts

198 months

Friday 5th June 2015
quotequote all
walm said:
Timmy40 said:
Then for a 24V battery assuming you have a suitable inverter I assume it's 24 * the AH divided by the wattage. To be honest I've only see 12V inverters to allow a 3 pin plugged device to run off a car batter anyway. Which is what most people would want to do.
OK - perhaps I jumped the gun.
Your rule of thumb will clearly work well for the most common use.

I don't know the wattage of my smoke detectors anyway and those duracells didn't have an Ah rating after all!
Fair enough.

It's just a rule of thumb I thought was handy, I've got a 1000W inverter with a 3 pin and there are various things over summer I fancy running off a car battery, so handy to have an easy way to estimate how long things will run for.

Negative Creep

24,983 posts

227 months

Saturday 6th June 2015
quotequote all
I stand to be corrected, but the way I understand it fewer means "not as many" whereas "less" means "not as much" i.e. something that cannot be counted. So why do we say "less than 10 minutes" or "less than a week away". Shouldn't it be fewer?

Dr Jekyll

23,820 posts

261 months

Saturday 6th June 2015
quotequote all
Why does the tilting of the earths axis that causes the seasons take exactly the same time to repeat itself as the earth takes to go round the sun?

grumbledoak

31,535 posts

233 months

Saturday 6th June 2015
quotequote all
Negative Creep said:
I stand to be corrected, but the way I understand it fewer means "not as many" whereas "less" means "not as much" i.e. something that cannot be counted. So why do we say "less than 10 minutes" or "less than a week away". Shouldn't it be fewer?
Fewer for things you would count as individuals, I think. So fewer people, less minutes.

Exige77

6,518 posts

191 months

Saturday 6th June 2015
quotequote all
Why is compost sold in Litres and not Kgs ?

Shaolin

2,955 posts

189 months

Saturday 6th June 2015
quotequote all
Exige77 said:
Why is compost sold in Litres and not Kgs ?
So they can fluff it up and rip you off. I used one "50L" bag yesterday, it filled 3 x 10L pots with nothing left over.

MissChief

7,111 posts

168 months

Saturday 6th June 2015
quotequote all
Same reason they sell ice Cream in litres or parts thereof. If they sold it via weight they wouldn't be able to rip you off as well.

Ayahuasca

27,427 posts

279 months

Sunday 7th June 2015
quotequote all
Negative Creep said:
I stand to be corrected, but the way I understand it fewer means "not as many" whereas "less" means "not as much" i.e. something that cannot be counted. So why do we say "less than 10 minutes" or "less than a week away". Shouldn't it be fewer?
Fewer is for discrete numbers of items.

'Less than 10 minutes' is a measurement of continuous time, involving maybe fractions of a minute, seconds, etc and it is not simply a measurement of the number of minutes involved.


'less than a week away' is the same.





MarshPhantom

9,658 posts

137 months

Sunday 7th June 2015
quotequote all
Ayahuasca said:
History question.

Why did Henry VIII not have his first wife, Catherine of Aragon, offed?

He had no qualms about offing later wives, and offing Catherine would have saved years of hassle and bother of breaking away from the pope and setting up his own branch of the church.

Was he more squeamish in his early days?
Didn't he have a riding accident which left him a changed man, he was a much nicer person in his early years than his later ones.

kev b

2,715 posts

166 months

Sunday 7th June 2015
quotequote all
Why is it when setting out on a motorbike ride that a single large insect will splat your visor right in front of the viewing area within seconds of the journey, then no more will hit that piece of visor until you have cleaned it off?
Whereupon another will land in the same spot within a mile and the process repeats, ditto for newly polished car windscreens.

deeen

6,080 posts

245 months

Sunday 7th June 2015
quotequote all
Dr Jekyll said:
Why does the tilting of the earths axis that causes the seasons take exactly the same time to repeat itself as the earth takes to go round the sun?
The "tilt" doesn't move or change, it's the fact that we orbit the sun while tilted that causes the seasons. I think.

MissChief

7,111 posts

168 months

Sunday 7th June 2015
quotequote all
deeen said:
Dr Jekyll said:
Why does the tilting of the earths axis that causes the seasons take exactly the same time to repeat itself as the earth takes to go round the sun?
The "tilt" doesn't move or change, it's the fact that we orbit the sun while tilted that causes the seasons. I think.
Deen is correct. The tilt stays the same so in the winter the northern hemisphere is tilted away so it's colder as were slightly further away from the sun. In the summer were tilted slightly closer so it's warmer.
TOPIC CLOSED
TOPIC CLOSED