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## Archive for the ‘Articles’ Category

### Adding time – Algorithm 2

Wednesday, July 8th, 2009

Adding or subtracting time – Algorithm 2.

Previous algorithm is described here: Adding Time

Are you looking for adding time calculator online? See our online tool : Hour Calculator

Step 1 – Convert your data (time) to the smallest unit (minutes or seconds)
Step 2 – Add the values received in Step 1
Step 3 – Convert obtained result back to the desired format

Comments:
Step 1
“The smallest unit” means that if your data is given without seconds,e.g. 2:10 (two hours, ten minutes),
there is no need to convert hours to seconds because the smallest unit is a minute.

How to convert minutes to seconds, hours to minute and hours to seconds?
To convert minutes to seconds, simply multiply number of minutes by 60 (there is 60 seconds in one minute).
To convert hours to minutes, multiply number of hours by 60 (there is 60 minutes in an hour).
To convert hours to seconds multiply number of hours by 3600 (there is 60 seconds in each minute and 60
minutes in each hour, so 60*60 = 3600)

Step 2
no comments needed, I hope. This is simple arithmetic addition (or subtraction)

Step 3
This is the hardest step of this algorithm. To perform minutes to hours or
seconds to minute conversion, we have to find quotient (integer part) and reminder (‘left over’ amount)
of the division by 60 (or 3600). How to calculate quotient and reminder – see examples.

Example 1

T1 = 10:20, T2 = 1:50 – both values could be minutes:seconds or hours:minutes but let’s assume hours and minutes.

Step 1 – Change hours and minutes to minutes (smallest unit is minute):
T1 = 10:20 = 10*60 + 20 = 620 minutes
T2 = 1:50 = 1*60 + 50 = 110 minutes

Step 2 – Adding:
T1 + T2 = 620 + 110 = 730 minutes

Step 3 – Change minutes to hours and minutes:
To convert minutes into hours and minutes, we have to divide number of minutes by 60 (number of minutes in one hour)
730/60 => quotient = 12, reminder = 10
How to calculate the quotient?
Simply, divide the numbers and throw decimal part away (730/60 = 12.16666…, so the quotient is 12)
How to calculate the reminder?
Simply, multiply quotient by divisor (12*60) and subtract obtained result from the divident (730 – 720 = 10)
or multiply thrown away decimal part by the divisor (60*0.166666… = 10)

The answer is 12 hours and 10 minutes (You can check the result using Hour Minute Calculator)

Example 2 (dealing with hours, minutes and seconds)

T1 = 10:20:25, T2 = 1:50:45

Step 1 – Converting hours, minutes and seconds to seconds (smallest unit is second):
T1 = 10:20:25 = 10*60*60 + 20*60 + 25 = 36000 + 1200 + 25 = 37225 seconds
T2 =  1:50:45 = 1*60*60 + 50*60 + 45 = 3600 + 3000 + 45 = 6645 seconds

Step 2 – Adding:
T1 + T2 = 43870 seconds

Step 3 – Converting seconds to hours, minutes and seconds:
Method 1 – finding number of hours and seconds first.
43870/3600 => quotient = 12, reminder = 670 (how to find quotient and reminder – see Example 1)
So, we get 12 hours and 670 seconds. 670 seconds equals to 11 minutes and 10 seconds (why? – try to guess :))
So, the answer is 12 hours, 11 minutes and 10 seconds.
Method 2 – finding number of minutes and seconds first.
43870/60 => quotient = 731, reminder = 10
that means, we have 731 minutes and 10 seconds. 731 minutes is equal to 12 hours and 11 minutes
(how to convert minutes into hours and minutes – see example 1)
So, method 2 gives us the same result: 12 hours, 11 minutes, 10 seconds. (Check the result using Hour Minute Second Calculator)

Notice, that in the algorithm described above there is almost no difference between adding and subtracting.
The only difference can be found in step 2 and it is simple arithmetic calculation.

### Adding Time

Monday, July 6th, 2009

Adding or subtracting time given in hours:minutes:seconds [hh:mm:ss] format.

Are you looking for adding time calculator online? See our online tool : Hour Calculator

Algorithm 1

Add hours, minutes,seconds saparately then, if number minutes or seconds exceeds 60 or are less then 0, adjust the answer.

Example 1 (Adding) – Let’s add 2:45:10(two hours, fourty five minutes, ten seconds) and 1:10:05

• Hours = 2 + 1 = 3
• Minutes = 45 + 10 = 55
• Seconds = 10 + 5 = 15

Our answer is 3 hours, 55 minutes, 15 seconds

Example 2 (Subtracting) – Let’s subtract the times form Example 1

• Hours = 2 – 1 = 1
• Minutes = 45 – 10 = 35
• Seconds 10 – 5 = 5

The answer is 1 hour, 35 minutes, 5 seconds

Example 3 (with adjusting) – Let’s add 2:30:10 and 1:45:55

• Hours = 2 + 1 = 3
• Minutes = 30 + 45 = 75 (75 minutes is 1 hour and 15 minutes because 75 – 60 = 15)
• Seconds = 10 + 55 = 65 (1 minute and 5 seconds)

Because number of minutes and number of seconds are greater then 60, we have to adjust (by adding 1) the number of hours and minutes, so the answer is 4 hours, 16 minutes and 5 seconds.

Example 4 (subtracting with adjusting time). Let’s subtract time from Example 3

• Hours = 2 – 1 = 1
• Minutes = 30 – 45 = -15  (-1 hour + 45 seconds)
• Seconds = 10 – 55 = – 45 (-1 minute + 15 seconds)

Because number of minutes (and seconds) is less then zero we have to adjust number of hours (and minutes) by subtracting 1. The answer is 0 hours, 44 minutes, 15 seconds.

Another algorithm for adding time is available here Adding Time – Algorithm 2

### Venus Williams serve speed

Tuesday, June 30th, 2009

Watching Venus Williams matches, one you can see that she has more powerfull serve struck then any other players. For example, during her last match on Wimbledon Tour (Venus Williams vs. Agnieszka Radwanska (poland)) her average first serve struck speed was over 110 mph (177 km/h, 49.17 m/s) when Agnieszka Radwanska served with the average speed of 95 mph (153 km/h, 42.47 m/s). Williams fastest serve during the match was 122 mph (170 km/h, 54.54 m/s). Radwanska fastest serve – 104 mph (167 km/h, 46.49 m/s).
Venus Williams holds current women record for fastest serve struck in a main draw event. She recorded 130 mph (209.2147 km/h, 58.12 m/s) at the Zurich Open.

Other Venus Williams serve speeds (source: wikipedia.org)

2003 Australian Open quarterfinal – 125 mph (201 km/h), 2007 French Open second round, 2008 Wimbledon final, 2007 US Open first round – 129 mph.[4] At Wimbledon in 2008, her average first serve speed was 115 mph (185 km/h) in the quarterfinal, 116 mph (187 km/h) in the semifinal, and 111 mph (179 km/h) in the final. She also had a higher average serving speed than then World No.1 Roger Federer as well as eventual men’s champion Rafael Nadal.

### EarthDay

Monday, April 20th, 2009

Since 1970 April 22 is known as International Earth Day designed to inspire awareness and appreciation for the Earth’s environment and popularize knowledge about our Planet.

Founded by the organizers of the first April 22 EarthDay in 1970, Earth Day Network promotes environmental citizenship and year round progressive action worldwide. Earth Day Network is a driving force steering environmental awareness around the world. Through Earth Day Network, activists connect change in local, national, and global policies. Earth Day Network’s international network reaches over 17,000 organizations in 174 countries, while the domestic program engages 5,000 groups and over 25,000 educators coordinating millions of community development and environmental protection activities throughout the year. Earth Day is the only event celebrated simultaneously around the globe by people of all backgrounds, faiths and nationalities. More than a half billion people participate in Earth Day Network campaigns every year. [wikipedia.com]

To celebrate EarthDay 2009, we have added some ‘Earth Facts’ in the table below.
If you are not familiar with the units given in the table or you just want to get other units, click on the value to get to the unit converter.

Earth Fact In meters Additional Info
Aphelion 152,097,701,000 1.0167103335 AU
Perihelion 147,098,074,000 1.0000001124 AU
Semi-major axis 149,597,887,500 0.9832898912 AU
Mean radius 6,371,000
Equatorial radius 6,378,100
Polar radius 6,356,800
Circumference equatorial 40,075,020
Circumference meridional 40,007,860
Circumference mean 40,041,470
Earth Fact In Meters/sec Additional Info
Orbital Speed (Average) 29,783 107,218 km/h
Escape velocity 11,186 40269.6 km/h
Equatorial rotation velocity 465.1 1,674.36 km/h
Earth Fact In square kilometers Additional Info
Surface 510,072,000 100%
Land Surface 148,940,000 29.2%
Water Surface 361,132,000 70.8%
Earth Fact Celsius Fahrenheit
Min Surface Temperature -89 -128.2
Max Surface Temperature 57.7 135.9
Mean Surface Temperature 14 57.2
Earth Fact Unit
Volume 1.0832073*1012 km3
Mass 5.9736*1024 kg
Surface Pressure 101.3 kPa
Orbital Period 365.256366 days
Sidereal rotation period 23h 56m 4.100s

Dictionary (Definition):
Aphelion the point in its orbit where a planet (Earth) is farthest from the Sun (opposite of perihelion)
Perihelion the point in its orbit where a planet (Earth) is closest to the Sun (opposite of aphelion)
Equatorial Radius radius measured from the center of the Earth to the point on the Equator.
Polar Radius radius measured from the center of the Earth to the polar.
Circumference equatorial Earth circumference measured along the Equator.
Circumference meridional Earth circumference measured through the poles.
Sidereal rotation period Average Earth day.
Orbital Period Of the Earth The amount of time it takes the Earth to travel once around its orbit.

Happy Earth Day!

### How many millimeters in a meter

Thursday, April 16th, 2009

Browsing Q & A sites like answers.yahoo.com, wiki.answers.com is not so hard to notice that many people post questions similar to: “How many millimeters are in a meter”, “How many milliliters are in liter”,  “How many meters are in a kilometer”, … . Authors of these questions probably don’t know that the metric system of measurement is established on the set of prefixes.

Let’s see some examples, how the names of units looks like:

Examples Of Length Units: Micrometer, Millimeter, Kilometer.
Examples Of Mass Units: Microgram, Milligram, Kilogram.
Examples Of Capacity Units: Microliter, Milliliter, Kiloliter.

You can easily notice that the names can be divided into two parts: prefix (micro, milli, kilo) and the name of the unit (meter, gram, liter).

Every prefix has its own meaning and always means the same part or multiplication of something. E.g.

micro means 1/1.000.000 (microgram, microliter, micrometer)
milli means 1/1000 (milligram, milliwatt, millisecond)
centi means 1/100 (centimeter, centiliter)
deci means 1/10 (decimeter, deciliter)
kilo means 1000 (kilometer, kilogram, kilowatt)
mega means 1.000.000 (megaton, megawatt )

All 24 metric prefixes (called si-prefixes), introduced and governed by Bureau International des Poids et Mesures
( International Bureau of Weights and Measures ), you can find here : metric prefixes list

Prefixes used in computing:
If you are a computer user, you should be familiar with prefixes: kilo, mega, giga, tera or (maybe even with) peta. The same names are used in SI-prefix system but there are small difference between metric and computing systems. Since informational systems are based on power of 2, kilo means 1024 units (bits or bytes) (1024=2^10), mega means 1024 kilos, giga means 1024 mega and so on. In the SI (metric) system next prefix is 1000 times bigger then the previous (kilo means 1000 units, mega means 1000 kilos, giga means 1000 megs, and so on)

Exceptions:
Generally, you can add every prefix to every unit name. It should be understandable and acceptable, however there are some ‘everyday language’ exceptions of this rule.
Exception 1: There is a widely used mass unit called ‘metric ton’. It is equal to 1000 kilogram. In everyday language we will say 1 ton rather then 1 megagram but 1 megaton, 1 kiloton, 1 gigaton is ok.
Exception 2: prefixes mega and greater(giga, tera, …) are often added to power (megawatt, gigawatt), energy (megajoule,gigajoule), pressure (megabar, gigapascal) units but ‘the metric man’ will say ‘thousand liters’ rather then ‘megaliter’ or 1000 kilometers or 1.000.000 meters instead of 1 megameter.

Answering the question in the title of this post:
There are 1000 milliliters in one liter. Remember prefix milli means 1/1000 (one thousandth) of something.
Respectively, there are 1000 millimeters in a meter and 1000 meters in one kilometer.