1. happyphysics.com Physics Lecture Resources Prof. Mineesh Gulati Head-Physics Wing Happy Model Hr. Sec. School, Udhampur, J&K Website: happyphysics.com

2. Chapter 1 Units, Physical Quantities, and vectors

3. happyphysics.com 1.1 The Nature of Physics  Physical theory Creativity at every stage

4. happyphysics.com 1.3 Standard and Units Any number that is used to describe a physical phenomenon quantitatively is called physical quantity Any number that is used to describe a physical phenomenon quantitatively is called physical quantity The most common unit used by scientists and engineers around the world is International System, SI The most common unit used by scientists and engineers around the world is International System, SI

5. happyphysics.com SI unit  Time: second  Time: second [s]  Length: meter  Length: meter [m]  Mass: kilogram  Mass: kilogram [kg]  Current: ampere  Current: ampere [A]  Temperature: kelvin  Temperature: kelvin [K]  Force: newton  Force: newton [N]

6. happyphysics.com Unit Prefixes 1 nm = 10 -9 m 1 nm = 10 -9 m 1μm= 10 -6 m 1μm= 10 -6 m 1 mm= 10 -3 m 1 mm= 10 -3 m 1 cm = 10 -2 m 1 cm = 10 -2 m 1 km = 10 3 m 1 km = 10 3 m

7. happyphysics.com 1.4 Unit Consistency and Conversions Equation must always be dimensionally consistent Equation must always be dimensionally consistent example: d= 10m, v = 2ms -1 and t = 5s example: d= 10m, v = 2ms -1 and t = 5s © 2005 Pearson Education

8. happyphysics.com 1.5 Uncertainty and Significant Figures Uncertainty is the maximum different between the measured vale and true value Uncertainty is the maximum different between the measured vale and true value Significant figures is used to indicated the number of meaningful digits Significant figures is used to indicated the number of meaningful digits example: 2.91mm ( 3 significant figures ) example: 2.91mm ( 3 significant figures )

9. happyphysics.com Table 1.1 Mathematical operation Significant figures in result Multiplication or division No more than in number with the fewest significant figures e.g. 0.745 x 2.2/3.885=0.42 Addition or subtraction Determined by the number with the smallest uncertainty e.g.27.153+138.2 – 11.74=153.6

10. happyphysics.com 1.7 Vectors and Vector Addition Scalar quantity is described by a single real number, it can be positive, zero or negative Scalar quantity is described by a single real number, it can be positive, zero or negative Vector quantity has both a magnitude and a direction in space. Vector quantity has both a magnitude and a direction in space.

11. happyphysics.com Displacement Displacement is the change of position of a point Displacement is the change of position of a point P2P2 P1P1 A The displacement form point P 1 to P 2 is vector A

12. happyphysics.com Displacement Displacement is always a straight-line segment directed from the starting point to the end point If the path ends at the same place where it started, the displacement is zero P2P2 P1P1 Displacement is not related directly to the distance traveled

13. happyphysics.com Vector Addition A B C =A+B

14. happyphysics.com AB C=A + B B A

16. A B C D R R = ( A+B ) + C = D + C

17. happyphysics.com Addition of vectors

18. happyphysics.com 1.8 Components of Vectors θ AxAx AyAy A

19. happyphysics.com R A B Ax Bx Rx By Ay Ry

20. happyphysics.com 1.9 Unit Vectors A unit vector is a vector that has a magnitude of 1 AxiAxi AyjAyj A i j Vector sum R:

21. happyphysics.com 1.10 Products of Vectors Dot product Dot product θ B A

22. happyphysics.com Example 1.10 53° 130° Find the scalar product of the two vectors. The magnitude of vectors are A=4.0 and B=5.0 Ans: = 4 ×5 cos 77° =4.5 B A

23. happyphysics.com Vector Product Vector Product θ A B A×B

24. happyphysics.com Right hand rule

25. happyphysics.com Summary

29. END Visit: happyphysics.com For Physics Resources