01 Intro to PHYSICS.pdf

GRADE 12 - STEM GENERAL PHYSICS 1 Simple History of Physics What do you usually think when you are asked what physics is? ANSWER: Difficult Boring Useless subject in high school. What do you usually think when you are asked what physics is? ANSWER: All of us practically “ea...

GRADE 12 - STEM GENERAL PHYSICS 1 Simple History of Physics What do you usually think when you are asked what physics is? ANSWER: Difficult Boring Useless subject in high school. What do you usually think when you are asked what physics is? ANSWER: All of us practically “eat” and “breathe” physics day in a day out. There is physics… whether we are at rest or in motion. in a ticking clock, in a hot flatiron and in ringing cellphone. In music and in light. WHAT IS PHYSICS Physics – is the study Physics – is of everyday phenomena. the study of matter and - It aims to explain energy and these phenomena in their terms of the relationship. fundamental laws, or the laws of nature. UNITS AND MEASUREMENT What are the effects of instruments on measurements? How are instruments on measurements affects your everyday life? PHYSICS without mathematics is unthinkable. A- S–M–D M–D–A–S G–E–M–D–A–S B–O–D–M–A-S MEASUREMENT: A Universal Language -process of comparing one quantity with another quantity. -are used to described such quantities as length, weight, area, MEASUREMENT: A Universal Language -is a quantitative description of a fundamental property or physical phenomena  Fundamental 1.Length (meter) Quantities 2.Mass (kilogram) 3.Time (second) 4.Electric current (ampere) 5.Thermodynamic temperature (kelvin) 6.Amount of substance (mole) 7.Luminous intensity (candela)  Derived Quantities Many other quantities can be derived out of the combination of the basic quantities. Examples: 1. For instance a speed is the ratio of a length by a time. 2. Acceleration is the ratio of a speed by a time. 3. And a force is the multiplication of  What do these measurements have in common? EXAMPLES OF DIFFERENT MEASUREMENT Diameter of the sun: Size of bacteria: 1, 391 400 km 0.0005 m Speed of Light: 299,792,458 m/s Distance of Earth from the Diameter of the proton: sun: 0.000 000 000 001 mm SCIENTIFIC Notation A compact way of writing over a wide range of values. Number are 5x 10 6 = 5000000 presented by the product of a 1024 mb = 1 multiplying factor Gb Express (a) 0.000 646 and (b) 5 430 000 in scientific Express (a)0.000 646 and (b)(b) 5 430 000 in scientific notation.  ANSWER: 6.46 x10-4 5.43 x 106  ACCURACY & PRECISION Accuracy and precision are used in context of measurement.  ACCURACY & PRECISION Accuracy refers to the closeness of a measured value to a standard or known value. For example, if in lab you obtain a weight measurement of 3.2 kg for a given substance, but the actual or known weight is 10 kg, then your measurement is not accurate. In this case, your measurement is not close to the known value.  ACCURACY & PRECISION Precision refers to the closeness of two or more measurements to each other. Using the example earlier, if you weigh a given substance five times, and get 3.2 kg each time, then your measurement is very precise. Precision is independent of accuracy. You can be very precise but inaccurate, as described above. You can also be  ACCURACY & PRECISION For example, if on average, your measurements for a given substance are close to the known value, but the measurements are far from each other, then you have accuracy without precision.