Puzzle-4 November 2018
A high school teacher wanted to demonstrate the Archimedes’s principle to his students. As you know, Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid.
That is, loss of weight of an object in any fluid = weight of fluid displaced by the object.
That is, loss of weight of an object in any fluid = weight of fluid displaced by the object.
He took aluminium vessel of 50cm height and diameter 5cm diameter. As he was planning to conduct the experiment the next day, he told his helper to fill the vessel full with kerosene, and he left the school.
Next day, he called all the students to the lab. He tied a steel ball having 100 cc volume and 800gm weight to spring balance with the help of a thin wire. (Volume of the hook and wire are negligible) and showed the students that the weight of the ball is 800gm in air.
Next day, he called all the students to the lab. He tied a steel ball having 100 cc volume and 800gm weight to spring balance with the help of a thin wire. (Volume of the hook and wire are negligible) and showed the students that the weight of the ball is 800gm in air.
He saw that the vessel was full and he felt the smell of kerosene. He carefully immersed the ball deep in to the vessel, holding the spring balance. He placed a plate below the vessel and collected the kerosene flowing out. He measured the volume and it was 100 cc. He measured the weight of that 100cc and it was 80gm, confirming that it was pure kerosene, because the density of kerosene is 0.8 and so weight = volume X density = 100 X 0.8 = 80gm. So, according to Archimedes’s principle, spring balance should have shown 800 -80=720gm. But the spring balance reading was 700gm!
What was the reason?
What was the reason?
Puzzle-3 October -2018
From high school, we have learnt that the center of gravity of a triangular lamina is at 1/3rd the height of the triangle from the base.
Let us consider an isosceles triangle, having 60 mm base and 60 mm height. So, the center of gravity must be at the point G, which is at 1/3rd the height from the base.
Here I have calculated the total area of the triangle . See the figure below.
Here I have calculated the total area of the triangle . See the figure below.
I have calculated the area of the triangle CDE. See the figure below. It is only 800 sq.mm. That is less than half of total area of 1800 sq.mm. How is this possible?
I have found out a point at which the areas are equal. It is shown in the figure below. It is the point F, which is slightly less than 1/3rd the height from the base.
So, all you have to do is to select the correct answer from the choice or if you feel that there is no correct answer in the choice, then click “I have my own answer” and click "next" to type your answer and submit.
This time, you can submit only once, so think before you submit. Send your answer in the form given below.
This time, you can submit only once, so think before you submit. Send your answer in the form given below.
Puzzle-2. September -2018.
A person who retired at 60 years of age in August 2018, purchased a 3 digit number code digital cash box. In order to remember the numbers easily, he stored 3 numbers form his date of birth . He wrote his date of birth in the form of DD- MM-YYYY. (Please see the picture above).He took the 1st digit from date and stored it as 1st digit of the code, 2nd digit from the month and stored it as 2nd digit of the code, 3rd digit from the year of birth and stored it as 3rd digit for the code. The following are the hints for the 3 digit number of the lock to open.
1] 1st digit is even number.
2]There are no zeros.
3]There are two even numbers.
4] the 3 digit number is divisible by 19.
FIND THE 3 DIGIT NUMBER.
YOU CAN TRY AS MANY TIMES AS YOU WANT, TILL YOU GET THE CORRECT ANSWER.
Type your answer in the form below.
Puzzle-1 ( posted on 25/07/2018)
There are six boxes each containing 100 marbles. All marbles are identical in size and appearance but of different colors mixed in each box. Weight of each marble is 10 gm in four boxes. But in one of the box, each marble weighs only 9 gm. In another box, each marbles weighs 11 gm.
There is a digital weighing machine, capable of weighing from 1 gm up to 999 gm.
Problem:
By weighing, you have to identify the box which is having marbles of 9 gm and the box which is having marbles of 11 gm.
Given conditions:
- The container placed on the weighing machine can hold a maximum of 50 marbles. That means, you are supposed to weigh not more than 50 marbles at a time.
- There is another similar container available but only one container should be placed at a time on the machine.
- You can even weigh one marble at a time or a maximum of 50 marbles but for each weighing ,you have to pay $1 for weighing machine owner.
Best answer is that which require minimum payment to the machine owner.
Last date for submitting the answer for the above puzzle-1 is 25/08/2018.
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