16
Dec
09

Solutions to WU’s puzzles and riddles : GLASS HALF FULL (easy)


Glass Half Full

I am trying to find all the solutions and put them together at a single place, So feel free to add comments and if you have a solution please do post. Cheers … 🙂
Here is the puzzles link : http://www.wuriddles.com/

Question : You are in an empty room and you have a transparent glass of water. The glass is a right cylinder, and it looks like it’s half full, but you’re not sure. How can you accurately figure out whether the glass is half full, more than half full, or less than half full? You have no rulers or writing utensils.

Hint 1: To help you get started if you’re stuck, here’s a solution that’s not good enough. Holding the cup upright, use the palm of your left hand to cover the cup’s opening. Now make a pinching gesture with the index finger and thumb of your right hand. Put the thumb at the base of the cup, and the index finger adjacent to the water level, thereby gauging the height of the water surface from the base of the cup. Now freeze the distance between those two fingers. Flip the cup upside down with your left hand; no water falls out since you’ve sealed the opening with your left palm. Now put your frozen right hand against the cup, and see if the inverted water level is next to your index finger. If so, the cup is exactly half full. This seems like a good solution, but it’s actually slightly accurate, because the palm of your hand is not a perfectly flat surface. Also, you’ll most likely lose some water when you flip the cup upside down. We want a really accurate method.

Hint 2: Utilize the geometry of the cup. That’s really important.

Hint 3: Don’t drink the water. ^_^

My Solution : Tilt the glass till the water comes upto the brim. If the glass is exactly half filled, then the 2 ends of the water will be the brim and the upper bottom of the tilted glass. If the water is less than half, the water level will be lower than the upper bottom of the tilted glass and vice versa. This is possible because, the glass is a right circular cylinder, which means that the length of the radius is equal to the height of the cylinder. Another explanations is through the volumes. If the glass is half full, then the volume of the water must be ∏ rˆ3/2 . And if the tilted glass has the water level touching the brim and the upper bottom of the glass then their volume will also be V/2 .

Advertisements

3 Responses to “Solutions to WU’s puzzles and riddles : GLASS HALF FULL (easy)”


  1. August 8, 2011 at 9:25 am

    Good solution. I didn’t think about that right circular property. It’s easy after knowing that. Thanks btw.

  2. January 9, 2017 at 9:38 am

    This is very simple. Pay attention. This is where the problem is for most people. Listening. Ok, listen , first and foremost there is no such thing as a half empty or half full . Full is full empty is empty. This is where people are going past A . The glass is 100% full all the time. I, will take a glass and put water into the glass until the half way point, using a ruler the glass now is 100% full. As, a matter of fact the glass is always 100% full.Let me explain. Here’s one way to explain it’s at the half way point and this goes for a sealed cylinder also .the problem is common sense. I, would presume you don’t know this because only 9 to 40 % of the population posses it. I,am not putting you down. It’s ok not to know for now . So, to make it clear. Number one. We have air, atoms, molecules, pressure, gravity xcerted on are bodies and everything else around use 14.7 psi ,15psia absolute. The glass, that everyone is having a problem with is 100% full all the time. Take the glass or cylinder cut it in half using a ruler. Take the liquid half put it on a flat surface. Now, is it 100% full? Yes, fact. Now, the other half, that is empty to most is 100%full of air, atoms,pressure and gravity. Now take the glass and so called cylinder and put them back where you removed them from and what you have is 100% over 100% = 1 full glass or cylinder all the time. Even if the cylinder was sealed, it had to be open at one point in time. That’s where air ect… gets in no matter what. I, don’t care if it is smaller than a pin hole. Was this common sense question helpful.

  3. January 9, 2017 at 10:04 am

    This is very simple. Pay attention. This is where the problem is for most people. Listening. Ok, listen , first and foremost there is no such thing as a half empty or half full . Full is full empty is empty. This is where people are going past A . The glass is 100% full all the time. I, will take a glass and put water into the glass until the half way point, using a ruler the glass now is 100% full. As, a matter of fact the glass is always 100% full.Let me explain. Here’s one way to explain it’s at the half way point and this goes for a sealed cylinder also .the problem is common sense. I, would presume you don’t know this because only 9 to 40 % of the population posses it. I,am not putting you down. It’s ok not to know for now . So, to make it clear. Number one. We have air, atoms, molecules, pressure, gravity xcerted on are bodies and everything else around use 14.7 psi ,15psia absolute. The glass, that everyone is having a problem with is 100% full all the time. Take the glass or cylinder cut it in half using a ruler. Take the liquid half put it on a flat surface. Now, is it 100% full? Yes, fact. Now, the other half, that is empty to most is 100%full of air, atoms,pressure and gravity. Now take the glass and so called cylinder and put them back where you removed them from and what you have is 100% over 100% = 1 full glass or cylinder all the time. Even if the cylinder was sealed, it had to be open at one point in time. That’s where air ect… gets in no matter what. I, don’t care if it is smaller than a pin hole. Was this common sense question helpful.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


Ads By Google

December 2009
M T W T F S S
« Nov   Jan »
 123456
78910111213
14151617181920
21222324252627
28293031  

Blog Stats

  • 622,084 hits

Pic of the week : Kai (Beyblade)

Top Rated

Archives

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Join 14 other followers


%d bloggers like this: