1 / 20

Chapter 1 Introduction to physics

Chapter 1 Introduction to physics. Dr. Haykel Abdelhamid Elabidi website: uqu.edu.sa/staff/ar/4331237 Email: haelabidi@uqu.edu.sa mobile: 0564518933. 2 nd /3 rd week of September 2013/DhQ 1434. Course Syllabuls. Course Syllabuls. Units of Chapter 1. Physics and the Laws of Nature

kemp
Télécharger la présentation

Chapter 1 Introduction to physics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 1Introduction to physics Dr. Haykel Abdelhamid Elabidi website: uqu.edu.sa/staff/ar/4331237 Email: haelabidi@uqu.edu.sa mobile: 0564518933 2nd/3rd week of September 2013/DhQ 1434

  2. Course Syllabuls

  3. Course Syllabuls

  4. Units of Chapter 1 • Physics and the Laws of Nature • Units of Length, Mass, and Time • Dimensional Analysis • Significant Figures • Converting Units

  5. 1- What is Physics • Physics is the study of the fundamental laws of nature. These laws can be expressed as mathematical equations. • It is the science of measurements and experimental. • Physicist (scientist who studies Physics) observes the phenomena of nature and try to find patterns and principles that relate these phenomena.

  6. 2- Units of Length, Mass and Time • To make quantitative comparison between the laws of physics and our experiments, certain basic physical quantities must be measured. • We use here three basic quantities: length (L), mass (M) and time (T). • Mohamed measures the length of the room wall with a ruler, he gives us a value of 5. • Abdullah measures the same length, he gives us a value of about 16. What is the real value of the length? We have to define the unitsusedwhenmeasuring the threequantities: SI (International System of Units) or mks mks (m: meter, k: kilogramme and s: second)

  7. 2- Units of Length, Mass and Time • Unit of Length: meter (m) One meter is the distance traveled by light in a vacuum in 1/299,792,458 of a second. See Table 1-1 page 3 • Unit of Mass: kilogramme (kg) One kilogram is the mass of a particular platinum-iridium (Pt– Ir) cylinder kept at the International Bureau of Weights and Standards, France. See Table 1-2 page 3 • Unit of Time: second (s) One second is the time required for a cesium(Cs)-133 atom to undergo 9,192,631,770 vibrations. See Table 1-3 page 4 The standard prefixes are used to designate common multiples in powers of ten. Exemples: 1mm =10-3m, 1km=10+3 m, 1cm = 10-2 m, 1micro= 10-6 m,1angstrom = 10-10m See Table 1-4 page 5

  8. 3- Dimensional analysis • The dimension in physics refers to the type of quantity regardless of the unit used. • Ex. a distance has a dimension of length, but the unitscanbemeter or feet or mile… • The dimension of a quantityisdenoted in brackets: • Length [L], Mass [M], Time [T] • Any valid physical formula must be dimensionally consistent (each term must have the same dimensions) • This type of calculation with dimensions is called dimensional analysis

  9. 3- Dimensional analysis

  10. 3- Dimensional analysis Exercise 1-2 page 5:

  11. 4- Significant Figures The quotient d/t is calculated using a calculator displaying 8 digits: d/t=(21.5 cm)/(8.5 s)= 2.4941176cm/s The result must be less accurate than the two given numbers : RULE 8.5 s 21.5 cm The number of significant figures after multiplication or division is equal to the number of significant figures in the least accurately known quantity. In our example: d is known to 3 significant figures the speed should be given with 2 significant figures: t is known to 2 significant figures d/t=2.5 cm/s t is the least known quantity

  12. 4- Significant Figures Example 1-1 page 6: A tortoise travels at 2.51 cm/s for 12.23 s. How far does the tortoise go? Answer: 2.51 cm/s × 12.23 s = 30.7 cm, and not 30.6973 cm only three significant figures You measure a time of 16.74 s, then you measure another time of 5.1 s The total measured time is 21.8 s, and not 21.84 s RULE The number of decimal places after addition or subtraction is equal to the smallest number of decimal places in any of the individual terms.

  13. 4- Significant Figures

  14. 4- Significant Figures

  15. 4- Significant Figures 2500 0.000036 Each of these numbers has two significant figures 2500 = 2.5 × 103 If we write 2.50x103, it has three significant figures 0.000036 = 3.6 x 10-5 Exercise 1-4 page 7 How many significant figures are there in (a) 21.00, (b) 21, (c) 2.1x10-2, (d) 2.10x10-3 ?

  16. 5- Converting Units We want to convert a distance of 225 ft to meters (m): We use the conversion factor 1m=3.281 ft and To make the conversion from feet (ft) to meters (m), we multiply 225 ft by the first factor (1 m/3.281 ft): To make the conversion of 24.3 meters (m) to feet (ft), we multiply it by the second factor (3.281 ft/1 m):

  17. 5- Converting Units Convert the distance d=3.00 mi to meters. 1 mi=5280 ft First conversion: mi ft: Second conversion: ft m: We can do this in a single calculation:

  18. 5- Converting Units Conversion involving any number of units: You walk at 3.00 m/h, how fast is that in ft/s ? 1h=3600 s We need the conversion of 3.00 mi to meters (this was done before) and then the conversion of 1h to seconds. → The speed will be 9.84 ft/s Conversion from hours to seconds:

  19. 5- Converting Units Active example 1-1 page 9: Blood in the human aorta can attain speeds of 35.0 cm/s. How fast is this in (a) ft/s and (b) mi/h? Solution: You can see also Example 1-2 page 9

  20. Homework: Ex.5; 6; 7; 8; 9; 11; 12; 13; 14; 15; 17 and 20 page 15 Thankyou for your attention Seeyounext time Inchallah

More Related