Answers

Q.1:Define :

1. – Measurement: The process of comparing an unknown quantity with another one of its kind ( called the unit of measurement ) to find out how many times the first includes the second .

2. – Fundamental physical Quantities: physical quantities that cannot be defined in terms of other physical quantities .

3. – Derived physical Quantities : physical quantities that can be defined in terms of the fundamental physical quantities .

4. – Standard Meter :The distance between two engraved marks at the ends of a rod made of platinum and iridium alloy kept at .

5. – Standard kilogram : The mass of a cylinder made of platinum and iridium alloy of specific dimensions kept at .

6. – Standard second :

The second =   1/  86400    of the average solar day.

7. – Dimensional formula : The formula that expresses the derived physical quantities in terms of the fundamental physical quantities (mass ‚length & time) each has a certain exponent .

8. – Absolute error : The difference between the actual value (xo ) and the measured value (× )=ןן

    

   

9. – Relative error: The ratio between the absolute error to the real value .

10. – Scalar quantity: the physical quantity that can be fully defined by its magnitude only .

11. – Vector quantity : The physical quantity that can be fully defined by both magnitude and direction .

12. – Distance : The length of the path moved by an object from a position to another . (Scalar quantity )

13. – Displacement : The change in the position of object ‚ or the length of the straight line segment in a given direction between the starting point and the end point .(vector quantity)

14. – Resultant force : A single force that results in the same effect on the object as that produced by the original acting forces . or ‚ the net force that affects an object as a result of the action of a number of forces .