Wednesday, July 21, 2010

How many hours in a year

Do you know how many hours are there in a year

How many hours in a year is nothing but the total hours we have in 1 year. Hours in a year can be calculated by using the multiplication of arithmetic process. We know that 24 hours is equal to 1 day. With the help of this we can find the hours in a year. We know that one normal year is equal to 365 days and one leap year is equal to 366 days.

Also get more details on days of our lives comings and goings

Important Terms to Calculate How many Hours in a Year

1 minute = 60 seconds
1 hour = 60 minutes
1 day = 24 hours
1 week = 7 days
1 year = 12 months
1 year = 365 days
1 leap year = 366 days

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Wednesday, July 14, 2010

How to find an Area of a Circle



The area of a circle is a simple shape of Euclidean geometry consisting of those points in a plane which are equidistant from a given point called the center. The common distance of the points of a circle from its center is called its radius.



Finding area of a circle

Example: 1Find the area of the circle with radius 14 meter
Solution:
We know the formula for finding the area of the circle = r2
Here r = 14 meter, = 3.14, substitute r and value in the above formula we get
Area = 3.14 * 142
Area = 3.14 *14*14
Simplify the above we get
Area = 615.44 meter square
Therefore the area of the circle is 615.44 meter 2

More details about area of a circle formula.

Thursday, July 1, 2010

Errors: Absolute and Relative Errors

Absolute Errors

Since no measurement is exact, there will always be the possibility of an error. Numbers are often rounded off to a certain number of significant figures or decimal places, and in such instances an absolute error can be calculated.

If the number 1200 is given to the nearest 100, for example, then the number can be anything between 1150 and 1250. It can therefore be written as 1200 ± 50. In this instance, the absolute error is 50.

In general, if a number is a ± b, then the absolute error is b.

Relative Errors

The absolute error doesn"t really tell us much about how big the error really is. For example, an absolute error of 1000 is very big if the number we are talking about is 3000, but it is small if we are talking about 100 000 000 000. The relative error incorporates the number that we are talking about.

If a number is a ± b, then the relative error is b/a

Example

If 200 is correct to 2 significant figures, what is the relative error?
This can be written as 200 ± 5, since the highest number it could be is 205 and the lowest is 195. The relative error, therefore, is 5/200 = 1/40 = 0.025 .

Percentage Error

Percentage error = relative error × 100

Absolute and Relative Error - Example Problems:

Absolute and relative error - Problem 1:

Student calculates the mass of a sample to be 5.65 g. Actual mass of the sample is 7.75 g. Determine the absolute error and relative error.

Solution:

Experimental calculated Value = 5.65 g

Known Value = 7.75 g

Absolute Error = Experimental calculated value - Known Value
= 5.65 g - 7.75 g
Absolute Error = - 2 g

Relative Error =

Relative Error =

Relative Error = - -0.29629 g.

Absolute and relative error - Problem 2:

Student calculates the mass of a sample to be 6.45 g. Actual mass of the sample is 8.42 g. Determine the absolute error and relative error.

Solution:

Experimental calculated Value = 6.45 g

Known Value = 8.42 g

Absolute Error = Experimental calculated value - Known Value
= 6.45 g - 8.42 g
Absolute Error = - 1.97 g

Relative Error =

Relative Error =

Relative Error = -0.233 g.

Hope you like the above definition and examples of Absolute and Relative Errors.Kindly leave your comments.