By age 44, you have blown only 990 birthday candles

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

02 December 2007

Today, I will answer some readers' questions that have remained in my waiting list for too long. The first is from Francis Mwangi who wants to know what would happen if a gun was fired in space. He wonders: "Due to lack of gravity, would the bullet go on and on forever? Would the path of the bullet be a straight line? Does the bullet have the equivalent force of impact as on earth? For how long can it possibly travel?"

Yes: IF there was no gravity, the bullet would go on for ever. That also answers the last question. However, as explained here a while ago, it is NOT true that there is no gravity in space. Even though you see astronauts "floating" inside the space shuttle, it does not mean that there is no gravity.

If you were inside a lift on the 20th floor of building and (God forbid) the support cables broke, you would also experience zero-gravity as you fall to the ground. Unfortunately, you might not live to tell the story!

Again, if we assume there is no gravity, then the bullet would travel in a straight line. The third question is a bit confusing; if the bullet is being fired in "space" - which I have taken to mean "far away from the Earth", then there is no equivalent impact on the planet.

However, the person holding the gun will be thrown back by the recoil from the bullet. He would fly "backwards" for ever (without stopping) but at a slower speed than the bullet.

***

Arthur asks an interesting one: "You know how at birthdays the blessing is 'may you live to blow a thousand candles'? Well, taking that on your first birthday you blow one candle, then two on the second birthday, three on the third and so on . by your third birthday you have blown six candles. At what age will a person have blown a thousand candles?"

That reminds me of another story: one day, a mathematics teacher didn't feel like teaching. So he went to class and gave the pupils this assignment: "Add all the numbers from one to 100". He was sure that this would keep them busy for the double-lesson.

But after about two minutes, one girl put her hand up and said the answer is 5,050. Shocked, the teacher asked her to explain how she got it so quickly. She said that she wrote the numbers in ascending order in one column and then in descending order in an adjacent column.

She then noticed that the sum of any two adjacent numbers was 101, e.g., 1 + 100 = 101; 2 + 99 = 101; 3 + 98 = 101; and so on. Since there were 100 numbers (1 to 100), the total sum for the two columns was 101 x 100 = 10,100.

But she needed the sum of only one column therefore she divided 10,100 by two to get 5,050.and you say girls aren't good in maths!

Anyway we can use this girl's idea to find out at which point one will have blown 1,000 candles. It turns out that after age 44, you will have blown 990 candles. Not very old!