Author Topic: car conundrum  (Read 2952 times)

Martin

car conundrum
« on: 17 October, 2017, 09:28:26 pm »
This has had a few cow orkers scratching their heads

a car drives a mile at 30mph; it then drives another mile.

How fast must it drive the second mile to average 60mph for 2 miles?

Re: car conundrum
« Reply #1 on: 17 October, 2017, 09:34:29 pm »
Well it's obviously not the obvious, but I'll say it anyway just to get it out of the way - 90mph
[crap at these kind of things]
Garry Broad

Feanor

  • It's mostly downhill from here.
Re: car conundrum
« Reply #2 on: 17 October, 2017, 09:35:19 pm »
This has had a few cow orkers scratching their heads

a car drives a mile at 30mph; it then drives another mile.

How fast must it drive the second mile to average 60mph for 2 miles?

To average 60mph for 2 miles, you must complete the 2 miles in 2/60 = 0.033333 hours.
If you have already driven 1 mile at 30 mph, you have already used 1/30 = 0.033333 hours.

You are already out of time.
You have no remaining time.
You would need to drive infinitely fast for the remaining mile.
You are DNF.

Re: car conundrum
« Reply #3 on: 17 October, 2017, 09:35:55 pm »
R17

In excess of c.

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Quote from: Kim
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Martin

Re: car conundrum
« Reply #4 on: 17 October, 2017, 09:37:23 pm »
This has had a few cow orkers scratching their heads

a car drives a mile at 30mph; it then drives another mile.

How fast must it drive the second mile to average 60mph for 2 miles?

To average 60mph for 2 miles, you must complete the 2 miles in 2/60 = 0.033333 hours.
If you have already driven 1 mile at 30 mph, you have already used 1/30 = 0.033333 hours.

You are already out of time.
You have no remaining time.
You are DNF.

correct!

Re: car conundrum
« Reply #5 on: 17 October, 2017, 09:38:56 pm »
R17

In excess of c.

(click to show/hide)

Depending on the observer you could make a case for c, relying on time dilation to allow you to travel the second mile in zero perceived time. In practice the acceleration would probably crush you...


Of course, someone will now point out that it's not possible to accelerate up to c due to general relativistic effects.


I'll get me coat

Martin

Re: car conundrum
« Reply #6 on: 17 October, 2017, 09:39:35 pm »
another one;

a man is pushing his car when he suddenly stops outside a hotel; suddenly he feels very disappointed

why?

Re: car conundrum
« Reply #7 on: 17 October, 2017, 09:39:51 pm »
Well it's obviously not the obvious, but I'll say it anyway just to get it out of the way - 90mph
[crap at these kind of things]
That would have been the correct answer if the question had had the car driving at 30 mph for one minute. If it then drove at 90 mph for a second minute it would have averaged 60 mph for the two minutes.
Quote from: Kim
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Re: car conundrum
« Reply #8 on: 17 October, 2017, 09:40:34 pm »
another one;

a man is pushing his car when he suddenly stops outside a hotel; suddenly he feels very disappointed

why?
Monopoly
Quote from: Kim
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Pingu

  • Put away those fiery biscuits!
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Re: car conundrum
« Reply #9 on: 17 October, 2017, 09:51:33 pm »
Was it one of those Google cars?

hellymedic

  • Just do it!
Re: car conundrum
« Reply #10 on: 17 October, 2017, 09:52:22 pm »
another one;

a man is pushing his car when he suddenly stops outside a hotel; suddenly he feels very disappointed

why?
Monopoly

And the hotel belongs to AN Other, who shouts RENT!

Re: car conundrum
« Reply #11 on: 17 October, 2017, 10:01:31 pm »
If it takes 5 minutes for 5 machines to make 5 widgets, how long does it take a 100 machines to make a 100 widgets ?
Rust never sleeps

Re: car conundrum
« Reply #12 on: 17 October, 2017, 10:10:14 pm »
5 minutes

Martin

Re: car conundrum
« Reply #13 on: 17 October, 2017, 10:53:20 pm »
not car related but make one 7 letter  one 5 letter one 4 letter and three 3 letter words (horizontal or vertical) using these letters only once each to fill in the gaps (it's supposed to be a pyramid)

Y Y R R E E A P U T H P

       P
    B - -
  T - - - -
 T - - - - - -

Martin

Re: car conundrum
« Reply #14 on: 17 October, 2017, 11:05:04 pm »
an equilateral triangle a square and a circle all have the same area; which has the longest circumference?

Jaded

  • The Codfather
  • Formerly known as Jaded
Re: car conundrum
« Reply #15 on: 17 October, 2017, 11:15:47 pm »
The Volvo  ???
It is simpler than it looks.

Re: car conundrum
« Reply #16 on: 18 October, 2017, 08:03:31 am »
an equilateral triangle a square and a circle all have the same area; which has the longest circumference?
Gut feeling, without checking formulae, says the triangle. Circle has the least.
<i>Marmite slave</i>

LittleWheelsandBig

  • Whimsy Rider
Re: car conundrum
« Reply #17 on: 18 October, 2017, 08:22:39 am »
MrC is correct
Wheel meet again, don't know where, don't know when...

Mr Larrington

  • A bit ov a lyv wyr by slof standirds
  • Custard Wallah
    • Mr Larrington's Automatic Diary
Re: car conundrum
« Reply #18 on: 18 October, 2017, 08:46:22 am »
If it takes a man and a half a day and a half to dig a hole and a half, how long does it take a fly with clogs on to walk through a barrel of treacle?

Show your working.
External Transparent Wall Inspection Operative & Mayor of Mortagne-au-Perche
Satisfying the Bloodlust of the Masses in Peacetime

Ben T

Re: car conundrum
« Reply #19 on: 18 October, 2017, 01:26:07 pm »
an equilateral triangle a square and a circle all have the same area; which has the longest circumference?
a triangle and a square don't have "circumference", they have perimeter.

hellymedic

  • Just do it!
Re: car conundrum
« Reply #20 on: 18 October, 2017, 02:02:48 pm »
an equilateral triangle a square and a circle all have the same area; which has the longest circumference?
a triangle and a square don't have "circumference", they have perimeter.

Indeed but pedants' threads are elsewhere.

Circles have the smallest perimeter for a given area and spheres the smallest surface area for a given volume.

Red blood cells are usually biconcave discs to increase surface area.
Spherocytosis (spherical red blood cells) is a known medical problem.

Martin

Re: car conundrum
« Reply #21 on: 18 October, 2017, 03:01:23 pm »
Red blood cells are usually biconcave discs to increase surface area.

possibly more to do with the ability to deform in small blood capillaries