Whe we first ran this problem it was casually assumed that re-entering rockets heated up due to air friction. Well, that’s not entirely true. The main reason is because the rocket’s heat shield is deliberately made blunt instead of aerodynamically pointy. The correct answer therefore is due to the compression of the air which heats it up and moves like a shield in front and around the rocket.
It also causes the hot shock wave to form at a distance, not immediately next to it. That separation acts like an insulation and reduces the amount of heat conducting into the rocket, leaving only scorch marks on its surface. With that in mind consider this question again: Can a pencil shaped (not blunt ended) log of wood be propelled fast enough underwater to heat up and burn?
THROUGHPUT
(The first one was: “Methuselah : Balthazar :: 6 : ?”)
Methuselah and Balthazar are Biblical characters. These names are also used to indicate wine bottles sizes. Methuselah is for a 6-litre bottle and Balthazar is for a12-litre bottle. So Methuselah : Balthazar :: 6 : 12. -- Mohanachandran R, mohanachandran@gmail.com
Methuselah is a biblical patriarch and a figure in Judaism, Christianity and Islam. Balthazar is traditionally referred to as the King of Arabia who gave the gift of myrrh to Jesus. The historic convention for naming wine bottle sizes is after biblical kings. Methuselah is the same size as an Imperial (6 litres) but the name is usually used for sparkling wines in a Burgundy-shaped bottle. Similarly, the size of Balthazar is 12 litres. So the missing value is 12. Hence, Methuselah : Balthazar :: 6 : 12. So there you go. -- Sushree Sulava, micky120795@gmail.com
(The second one was: “A hundred coins are in front of you. Ten of them are heads, the rest are tails and you’re blind. Your problem is to split the coins into two piles so that there’s the same number of heads-up coins in each pile.”)
You want equal number of heads in each pile. There are currently 10 of them. You don’t know which but it doesn’t matter. All you have to do is take any 10 coins out of the 100, put them into a separate pile, and flip those 10 over. That’s pile #1. Pile #2 is the remaining 90 coins, unflipped. Just leave them. You’re done. – Meenakshi Raghavan, meeravan32@gmail.com
Start with 10 coins laying flat on the table with 4 heads up (in random order), which is (H T T T H T T H H T). Now, just divide these coins in piles of 4 and 6 randomly. Let it be as (H T T T) (H T T H H T). Now, flip over all the coins of the shorter pile which now becomes (T H H H) (H T T H H T). Thus, the same number of heads-up appears in each pile. Hence, for 100 coins with 10 heads up, divide them into piles of 90 and 10, and etc, etc -- Shashi Shekher Thakur, shashishekher@yahoo.com
(And the last one was about a guy who buys 100 kgs of berries for 2.00 bucks/kg and expects to double by selling them at 4.00 bucks/kg. But he manages to sell only 50 kgs on the first day. The berries which had a 99% water content dehydrated and then had only 98%.. So what profit did he make?”)
He sells the first 50kg berries for 4.00 so that’s 200 bucks. The rest 50kg has 99% water so 1% is mass. When the water drops to 98% mass becomes 2%; hence weight drops to half ie 25kg. He sells it for 4.00 bucks to get 100 bucks. So in total he gets 300 bucks and a profit of 100 bucks. -- Reuben Thomas, reubenmammensunil@gmail.com
Since the farmer covers cost of his investment on first day and on second day, his 50 kg of fruit would weigh only 25 kg due to dehydration, he would get only 100 bucks and hence makes 50% profit on his investment. -- A V Ramana Rao, raoavr@gmail.com
BUT GOOGLE THIS NOW
Elkhart is camping at night near a ruined castle on the outskirts of Morovia. It’s very dark there. He has a torch that requires two batteries to light up. But then he realises that he’s got a total of eight batteries out of which four are charged and four are not. He doesn’t know which batteries are charged and which ones are not. (What to do, he’s dumb!) What’s the least number of attempts Elkhart needs to light up the torch?
Sharma is a scriptwriter and former editor of Science Today magazine.(mukul.mindsport@gmail.com)