Down A Hole!

Classical Mechanics Level 1

A ping-pong ball fell into a narrow pipe metal pipe, one foot deep, embedded in concrete. How would you get it out undamaged?

You have:
1. Ping Pong Paddle
2. Shoe Laces
3. A Bottle Full Of Water
4. A Hammer

With which one could you take the ball out easily?

A Hammer Shoe Laces A Ping Pong Paddle A Bottle Full Of Water

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Anish Harsha by Anish Harsha , 20, India

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15 solutions

Anish Harsha
Jul 11, 2015

If we pour the water into the metal pipe, due to Archimedes's principle, the ball starts to float and it rises on to the surface and we can pick it up easily. So, the correct answer is, The Bottle Full of Water.

14 Helpful 0 Interesting 0 Brilliant 0 Confused
Nastacio Tafoya
Jul 18, 2015

If the ball hits a switch in the pipe permanently deactivating the artificial gravity field on your space ship, you are screwed.

7 Helpful 0 Interesting 0 Brilliant 0 Confused

Why would I keep the switch to my space-ship's angular momentum-based artificial gravity inside a random pipe? And why would I have said pipe embedded in concrete?

Utkarsh Chaturvedi - 5 years, 3 months ago

Yeah the rest of the solutions are pretty good but what if the ball's diameter leaves no space for the water to go underneath it?

5 Helpful 0 Interesting 0 Brilliant 0 Confused

The ball must have a smaller diameter than the pipe, only then it might have been stuck in it, Otherwise there wouldn't be a problem.

Anoushay anwer - 5 years, 4 months ago

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I reread the question. Seems like I earlier thought that the pipe was bottomless, and therefore deduced that the ball got stuck somewhere in between due to structural inconsistencies in the pipe. Thanks for correcting the fallacy in my statement.

Utkarsh Chaturvedi - 5 years, 3 months ago

Exactly my freind you are right .

Pradyumna Gupta - 5 years, 5 months ago
Nandik Devbhuti
Aug 8, 2015

On poring the water into the metal pipe the ball will start to float which then gradually rises near the surface of the pipe. Then we could easily pick the ball without getting it damaged at all. And thus the correct answer is option (3).

Archimedes Principle.

5 Helpful 0 Interesting 0 Brilliant 0 Confused
Michael Vilabrera
Jul 17, 2015

the ball is lighter than the water, so it will float when water is poured into the hole

2 Helpful 0 Interesting 0 Brilliant 0 Confused
Juan Torres
Aug 4, 2015

Make the ball float using the water.

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Jonathan Chen
Jul 18, 2015

Ping Pong balls float.. the end

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Hadia Qadir
Jul 18, 2015

because in these options ''A Bottle Full of Water'' is the only solution. only water can prevent from damages. Archimedes's principle .The ball then according to his rule will start floating

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Mansi Jain
Jul 18, 2015

by archimedes's principle the answer is a bottle full of waterr.............:)

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Lance Fernando
Jul 18, 2015

The rule of buoyancy states that a light object,when with water, floats - so you could get the ball already once you fill in thewater.

1 Helpful 0 Interesting 0 Brilliant 0 Confused

An iron filling is light. Why does it not float?

Jake Lai - 5 years, 11 months ago

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It's because the iron filling has its own hard density - know what I mean?

Lance Fernando - 5 years, 11 months ago
Arun Garg
Apr 7, 2016

you should read "thirsty crow" for this. ha ha ha ha

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Nitin Kumar
Mar 17, 2016

Ping ball is lighter than water so ball will floar.

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Anuj Agarwal
Feb 10, 2016

there is one doubt though. Since the quantity of water isn't specified, how can we be so sure that 'one' bottle of water will be enough to take out the ball .....???

0 Helpful 0 Interesting 0 Brilliant 0 Confused

The OP put a pic of the bottle in the question, so it's not hard enough to figure out the quantity of water. Also, the pipe is narrow and one feet long. With an assumed radius of 1 cm, the cross-section area becomes approx 3.14 cm^2. Ultimately, the volume of the pipe comes out to be 94.2 cm^3 or 94 ml. The bottle will have enough water to handle the situation.

Utkarsh Chaturvedi - 5 years, 3 months ago
Ishita .S
Aug 25, 2015

When we pour water in the metal pipe the ping -pong ball starts floating due to the archimedes's principle

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Jingyang Tan
Jul 13, 2015

just pour water and the ball will float

0 Helpful 0 Interesting 0 Brilliant 0 Confused

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