Let’s say you’re one of those licensed physicists -- you know the type we call when some of the physics in our houses suddenly stops working -- and you then repair the stuff in a jiffy. Meaning if you’re one of those then don’t even try the following problem because you’ll solve it in a few seconds and keep crowing into the sunset for days. But if you’re a person who’s just interested in the stuff and maybe discovers a law or two from time to time, you’re welcome.
Hold a pencil three inches above a white sheet of paper under a fluorescent tubelight such that the pencil is parallel to the tubelight and observe its shadow. Now rotate the pencil through 90 degrees. Why does the shadow change and almost disappear?
THROUGHPUT
(The one from the wayback machine was: “Discovering his scales are faulty, a grocer weighs customers’ orders in two halves, putting the first half in the left-hand pan and weights in the right, then vice versa. Is this fair to both his customers and himself?”)
There can be two types of faults. When it’s due to difference in the weight of the pans, but the arms are of the same size, then if half the quantity is weighed with weights on one side and the remaining with weights on the other side, the total weight will be fair for both the seller and the buyer. When it’s due to the difference in the length of arms but the pans weigh equal, carrying out the same procedure may be unfair either to the seller or buyer. -- Dhruv Narayan, dhruv510@gmail.com
(The second one was a reader problem: “In a beaker, oil is floating in water. But for all floating bodies, a portion of the body lies below the water surface (depending on its density). So why does the whole oil float?”)
In the beaker the oil occupies the whole upper surface of water and hence no part is seen to be below the water as there is no space to displace the water as per Archimedes principle. However if you were to place a drop of oil on the water surface in the beaker you will see a part below the water as the water will be displaced and it will behave just like a solid floating body. -- Shyam Lakshminarayanan, orthoshyam@gmail.com
Two interesting asides. (1) If the same oil is filled in a thin balloon, so that the oil fills the balloon fully without air bubbles, and is placed on the surface of water, part of the balloon will be underwater. (2) If a drop of oil is placed on the water surface and if the oil retains its shape due to cohesive forces, instead of spreading and forming a thin layer, it will dent the surface of water. -- Balagopalan Nair K, balagopalannair@gmail.com
(The third one was . . . yes, yes, yes, less than a no brainer. Happy? But at least it was given as cannon fodder because a modder of all problems given earlier was not touched by any of you. Remember? Or are you happy in your somnolence?)
Naveen Patnaik born in 1946, present age 71, is CM for 17 years, assumed office in 2000. Total is 4034 that is double of the current year. Mamata Banerjee born in 1955, present age 62, is CM for 6 years, assumed office in 2011. Total 4034. (Year of birth) + (age in a particular year) = (the particular year). Similarly, (year of taking office) + (number of years till the particular year) = (the particular year). Adding the two, we get double the particular year. Your particular year was 1944, mine 2017. Good fun.
Abhay Prakash, abhayprakash@hotmail.com
I was born in 1950. So my age is 67. I assumed office in 1973 so it is 44 years since then and if you add all you get 4034. You were born in 1947 (pure guess). So your age is 70. Assuming you took charge somewhere in 1968 it is 49 years since then and adding it all you get 4034. You can try with some of your friends’ details and still get 4034. -- A V Ramana Rao, raoavr@gmail.com
BUT GOOGLE THIS NOW
1. There are three clocks with all telling different times: 11:55, 12:25 and 1:05. Each of them is a different number of minutes out compared to the actual time and, on an average, they are 30 minutes out. What’s the actual time?
2. What is the numerical value of PLASTERING, given that each of its alphabets stands for a different digit from among zero through nine and such that PANS, TIER, and SNAP are three square numerals, and SPA is a factor of PLASTERING?
Sharma is a scriptwriter and former editor of Science Today magazine.(mukul.mindsport@gmail.com)