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Math help needed


Airehead
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3 minutes ago, maddmaxx said:

When calculators replaced the abacus the doors were left open.

I only used 5 decimal places. Not precise enough to land a rover on mars, but close enough for doggy running IMO :) 

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This is one of the problems I'd give to my high school physics kids when I was teaching them how to solve problems by dimensional analysis if they can't remember the formula for doing it or if there is no standard formula.

You have 100 yards and 11 seconds and want miles per hour.

First you multiply the yards/second by 1 mile/1760 yards so the yards cancel out and you add miles to the numerator.

Then you want to cancel out the seconds in the denominator and replace it with hours, so you multiply by a number with seconds in the numerator and hours in the denominator:  60x60 seconds/hour or 3600 seconds/hour:

100 yards/11 seconds x 1 mile/1760 yards x 3600 seconds/hour = 100/11 x 1/1760 x 3600/1 miles/hour = 19 (rounded) miles/hour.

In science, you are only entitled to as many significant figure (digits) in the answer as there are in any of the measured numbers.  Assuming 100 is measured to the nearest yard, 100. is three significant figures. 11 seconds is two significant figures if it's measured to the nearest whole second, which would require that the answer be rounded to the lower measured significant figures, two.

The calculator says the answer is 18.5950413 etc. but since we don't know how many places seconds were measured to, it could be 11.1 seconds or 10.9 seconds, etc. rounded to the nearest whole number, so all the digits past 18 can't be sworn to so the number must be rounded: 19.

If the seconds are measured to 11.0 seconds, the answer is 18.6.  If the yards are measured to 100.00 and the seconds are 11.000, then the answer is 18.595 and so on.

 

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Are we talking land speed or air speed? When my wife would get home from work our Aussie would run out the hallway and jump when she reached the stairway, fly across the living room bank off the back or the couch and run back down the hallway. She would do this three or four times before my wife reached the top of the stairs. 

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My base calculator doesn't have yards per sec, but 300 feet divided by 11 = 27.272727273 feet per second

with feet per second....

18.59473159 miles per hour
29.92531972 kilometer per hour
8.3125881 meters per second
16.15837998 Knots
0.00000002772781165 speed of light :o
0.02422082987 Mach (speed of sound) :frantics:

Convenient app, Units Plus, on my phone at the ready with 12 conversion modules. Using the "Speed" module in this case.

 

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I'm not good at math, but I'll side with anyone nerdy enough to try it.. 
Heck.. I stood in Walmart yesterday trying to MATH. I was trying to figure out if 1 gal honey goes into 5 gal, will 80 oz be enough to make meed with for 3 gal. 

I almost hurt my thinking noodle but REFUSED to call my wife for help! 

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58 minutes ago, KrAzY said:

I'm not good at math, but I'll side with anyone nerdy enough to try it.. 
Heck.. I stood in Walmart yesterday trying to MATH. I was trying to figure out if 1 gal honey goes into 5 gal, will 80 oz be enough to make meed with for 3 gal. 

I almost hurt my thinking noodle but REFUSED to call my wife for help! 

Holy schitt!  You can buy honey by the GALLON at Walmart?  Wow!

 

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5 minutes ago, Philander Seabury said:

Holy schitt!  You can buy honey by the GALLON at Walmart?  Wow!

 

Well it's more of a 5lb jug, and two make a bit over a gal. The jug was an 80oz for $12 something. That is just like .65 of a gal, so technically two just would bring me above a gallon 

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On 7/2/2021 at 10:31 PM, Thaddeus Kosciuszko said:

Should we assume the dog is not an Airedale, but a good dog nonetheless, and that the good dog reaches 1/3 of his final speed in the first second, 2/3 of his final speed in the second, and then maintains his final speed during seconds 3 through 11, then I'd suggest the dog's speed as he flashes across the finish line would be about 20.5mph.

I'd say this is a good guess...     (average speed would be too slow)

I know... a Greyhound is faster than an Airedale, I was looking for how fast a dog can accelerate from standing still. 

a greyhound can reach a speed of 45 mph (72km/h)  within its first six strides from a standing start. :frantics:

According to dog expert Stanley Coren, “When Usain Bolt set his 100 meter world record he was running at a speed of 22.9 mph and covered that distance in 9.58 seconds. A greyhound would complete that same race in 5.33 seconds.” 

Then I found out my Jack Russell is (or at least was) a FAST dog.  Jack Russells can run as fast as 30 miles per hour, covering short distances in lightning bursts.     Last year, Parker was only living with us for a few weeks, when went outside and we took him outside with no leash, he noticed something...  I thought I'd never see him again.    Thank god, he is 13 years old,  I was able to eventually catch him.

@Airehead  maybe  @maddmaxx can figure out a way to use his fancy data logger (for his drag racing cars) to measure how fast your dog can sprint?

 

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