March 2014

Science: For the past 24 years, Mark Z. Jacobson, a professor of civil and environmental engineering at Stanford, has been developing a complex computer model to study air pollution, energy, weather and climate. In light of these recent model studies and in the aftermath of hurricanes Sandy and Katrina, he wondered What would happen if a hurricane encountered a large array of offshore wind turbines? Would the energy extraction due to the storm spinning the turbines' blades slow the winds and diminish the hurricane, or would the hurricane destroy the turbines? Read more ....

Imagine living on a planet with seasons so erratic you would hardly know whether to wear Bermuda shorts or a heavy overcoat. That is the situation on a weird, wobbly world found by NASA's planet-hunting Kepler space telescope. Read more ....

NASA's Kepler mission has announced the discovery of 715 new planets. These newly-verified worlds orbit 305 stars, revealing multiple-planet systems much like our own solar system. Read more .....

University of Georgia marine scientists are uncovering the mechanisms that regulate the natural production of an anti-greenhouse gas. A National Science Foundation grant will allow the UGA-led research group to further document how genes in ocean microbes transform sulfur into clouds in the Earth's atmosphere. Read more ....

The heroes and villains in animated films tend to be on opposite ends of the moral spectrum. But they're often similar in their hair, which is usually extremely rigid or - if it moves at all - is straight and swings to and fro. It's rare to see an animated character with bouncy, curly hair, since computer animators don't have a simple mathematical means for describing it. Researchers have provided the first detailed model for the 3-D shape of a strand of curly hair. Read more ....

## Solution

Okay, this is the answer that I get. Let me know if I am right. let the distance from my home to the office be "d" kilometres. On the first day, distance = d, speed = 10 and let time taken = t1. Therefore, 10 = d/t1. So, t1 = d/10.

On the second day, distance (it will be the same) = d, speed = 15 and let time taken be t2. Therefore, 15 = d/t2. So, t2 = d/15.

On the first day I reached at 1pm, and on the second day I reached at 11am. So the difference is 2 hours. Therefore, t1 - t2 = 2 (t1 is obviously greater than t2 because speed is less).

Therefore, d/10 - d/15 = 2.

Therefore, d = 60 kilometres.

Consider any of the two equations: t1 = d/10 or t2 = d/15 to determine the starting time. Let's take t1 = d/10. So, t1 = 60/10. Therefore, t1 = 6 hours. So on the first day it took me six hours to reach office. I had reached at 1 pm, which means I had started at 7am. (The second equation will give me the same result, obviously. Let's try it. t2 = 60/15. So, t2 = 4 hours. On the second day it took me four hours. I had reached office at 11am which means I had started at 7am).

So, I start at 7am and wish to reach office at 12 noon. This means I have to cycle for five hours. Now I can easily calculate the speed with which I should cycle. Distance = 60 and time = 5, so speed = 60/5 or 12 kmph.

By the way, if I have to cycle 60 kilometres to office and then 60 kilometres back home every day, I need to be a Superman.

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