Knowing and Living Some Science

Relevance of Physics to Life

Some questions you should already know the answer to

Why you feel cold when you have fever. Why you choose to reduce energy

consumption at home. What happens to your mental capacity when

your body lacks sleep. Why most computer parts and accessories

are painted black. Why girls mature first than boys, get

pimples first than boys. Why boys become aggressive when they

reach puberty.

The demand from you at this point.

How do you demonstrate understanding of the relevance of Science and technology to daily life?

The main goal of science

SCIENCE LIFE

Responsible living

Productive living

Progressive culture

Improved quality of

living•Conservation•Preservation•Health and Fitness•Green technology

•Computers and gadgets •Productivity tools

•Communication•Education•Medicine

•Improved media•More diversity in skills

The Science

When you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot measure it, when you cannot measure it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts advanced to that stage of a science. - Lord Kelvin

How well do you describe?

Qualitative vs. Quantitative Data Qualitative descriptions are sometimes

subjective and difficult to replicate. Quantitative descriptions are numeric

and can be replicated with a degree of exactness.

How do you measure?

Compare the physical quantity to a standard.

Self study: The different standards; Table 1-1

Assessment

How do you “measure” the character of a person around you? What is your standard?

Assessment

Where does Science start and to where does it lead?

Always remember

Start of science – desire to find the truth and establish a fact (observation, measurement, experiment)

Quantitative – more accurate (than …), obtained through measurement

Measurement – compare with standard

Significant figures

Determine the number of significant digits in the numbers below.

1. 1.232. 3.053. 0.002

The rules of significant figures does not apply to the figures above. The rules apply only to measurements.

Exercise 1

Count the number of significant digits in the figures given.

1.5.00 cm2.100 km3.0.054.0.200 cc

3103

Count the number of significant digits in the figures below:

1. 23.15 m2. 1.005 s3. 94.00 kg4. 1000 L5. 56,000 nm

6. 0.002 ml7. 200.0 cm8. 1.002009. 0.0300 s10.

mi

Separate ExercisesREVIEW AND PREPARE

Quiz yourself with the items on page 25, numbers 9-12.

Write your answer just below the exercise you shaded yellow.

Prepare to volunteer to show your answers on the board.

TELL ME WHAT YOU THINKStudy page 20 of your book. Focus on rule # 2 , sample 1.11 and prepare to share insights on this example.

Write your insight just below your exercise result that is shaded green.

Prepare to discuss it with a pair and with the group.

REM

ED

IAL

Perfect Seven

Determine the number of significant digits in the following figures.1. 0.150 mm2. 1.0800 cm3. 3.500 4. 0.002 kg5. 6,500 tons6. 405 seconds7. 1000.0 watts

Significant Figures

What’s with all the counting?

How well do you measure?

Accuracy describes how close the measurement is to correct value.

Precision describes how well a certain measurement is replicated.

Precision vs. Accuracy

Examples

The measure of the thickness of wood and its width are given as follows:

TRIAL #THICKNE

SSWIDTH

1 2.18 mm 3 cm

2 2.15 mm 3 cm

3 2.16 mm 3 cm

4 2.17 mm 3 cm

Average 2.165 mm 3 cm

Significant digits

Why do we count significant digits in measurement (only)?

Why are the rules like that? In counting the significant digits In addition (subtraction) In multiplication (division)

Why count SF?

The number of significant digits describe the degree of accuracy of the measurement.

Between these measurements, which is obtained using a better tool?

3 cm 2.18 nm3.00 cm

Always remember

Accuracy of measurement is quantified using significant figures. (depending on the tool and the skill) greater

SF – more accurate

A measurement is a comparison to a standard. Like when you say 1.5 kg, you are actually

saying “one and a half of the Le Grand K.” So 1.5 itself is meaningless without that kg

unit.

Preserve the degree of Accuracy

When a measurement is converted, its level of accuracy must be preserved.

Examples: 3 cm 0.03 m 3x107 nm 0.00003

km 12 in1.0 ft 0.33 yd

Exercise 1

Convert the following measurements in the units indicated.1. 1.0 kl to ml

2. 40 nm to cm

1.0x106 ml1,ōoo,ooo

ml

4x10-6 cm0.000004

cm

Answers

Separate ExercisesAnswer this exercise.½ crosswiseThe human brain is a super computer. It can store 10ō trillion bits of information. Express this number using all the prefixes h, da, d, c, m, and a in table 1-2.(Observe the correct scientific form)R

EM

ED

IAL

Answers

1.00x1012 hb1.00x1013 dab1.00x1015 db1.00x1016 cb1.00x1017 mb1.00x1032 ab

Exercise 2

Convert the following measurements in the units indicated.1. 1.230 g to μg2. 0.06 km to pm3. 5001 kB to GB4. 80 cl to L5. 20.0 nF to μ F

Assignment

Convert the following measurements in the units indicated.

1. 4.50 cm to km2. 300 L to kl3. 0.070 μg to ng4. 75,000 mg to cg5. 400,ō00 nm to km

How to illustrate quantities with directions

Directions will be represented by the axes of a Cartesian plane. North and East take the positive

direction, South and West the negative direction. N

EW

S

Example

A = 10m NortheastB = 5m East

A

B

R

Example

O = 10m 30O North of EastP = 5m East

O

P

R

Example

M = 10m 30O East of NorthN = 5m East

M

N

R

Illustrate the following quantities

A = 30m S30oE B = 15m W6ooN

How to find R

Simple Triangles (Right Triangles) M = 10m North N = 5m East

R2=M2+N2 M

N

R

Example

M = 10m 30O East of NorthN = 5m East

M

N

R

θ

Seatwork 1.1 (20pts.)

Open your book on page 45. Show your solution for #s 1, 2 and 4 of

letter B. Point distribution

#1 – 5pts. (5 minutes) #2 – 10pts. (10 minutes) #4 – 5 pts. (5 minutes)

Use your notebook #1 will be checked first before you

solve for #2.

Guidelines

Express your final answers in 2 SF. Always use figures using 2 digits after

decimal point for computation of final answers.

No partial points for wrong answers. Deductions for R and angle:▪ -1 each wrong/no unit ▪ -1 each wrong SF▪ -1 each improper placement of sign

Answers

24 m, 25O

120 m, -84O

1.6 m, -39O

Homework

The difference between each pair of the following terms must be in your notebook or in your head. Scalar vs. vector quantity Distance vs. displacement Speed vs. velocity Uniform motion vs. accelerated motion Kinematics vs. Dynamics