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The study of nature: models and measurements 2 © Zanichelli editore 2015

The course of scientific discovery 3 © Zanichelli editore 2015

The scientific investigation of nature 4 Biology, chemistry, physics and Earth science investigate natural phenomena and their causes. These disciplines study matter and its transformation. They are based on the experimental or scientific method. © Zanichelli editore 2015 Galileo Galilei, one of the fathers of the scientific method

The scientific method 5 Observing a phenomenon Formulating a hypothesis, making predictions Testing the hypothesis through experiments Collecting and interpreting data Do data confirm the hypothesis? Sharing results with the scientific community Yes No © Zanichelli editore 2015

Measurements and analysis 6 In order to study natural phenomena, you must: take meticulous measurements; analyse and interpret the results of the measurements. © Zanichelli editore 2015

Laws and scientific theories /1 7 Knowledge proven by experiments is summarised and organized as laws, which allow us to predict the behaviour of a specific phenomenon, but not always explain its causes. A physical law is Newton's universal law of gravitation which describes the attraction between two objects with mass. © Zanichelli editore 2015

Laws and scientific theories /2 8 Scientific theories are developed in order to explain a phenomenon. Each theory is continuously checked against reality and can be changed or updated. The idea behind Darwin's theory of evolution is that all species have evolved from simple life forms. © Zanichelli editore 2015

Models to describe nature 9 A scientific model is the representation of a complex phenomenon through images, mathematical equations or chemical formulae, in order to make it easier to understand. Many Solar System models have been built during the centuries to illustrate the relative positions and motions of the planets and moons in the Solar System. © Zanichelli editore 2015

Quantities and units of measurement 10 © Zanichelli editore 2015

Measurable properties: quantities 11 Bodies and materials have measurable properties called quantities. For each one of them there is a unit of measurement. © Zanichelli editore 2015

The International System / 1 12 Base quantitySymbol Name of the unit of measurement Symbol of the unit of measurement Lengthlmeterm Massmkilogramkg Timetseconds Electric currentiampereA TemperatureTkelvinK Amount of substance nmolemol Luminous intensityiviv candelacd © Zanichelli editore 2015 The International System of Units (SI) recognizes seven base quantities.

The International System / 2 13 Derived quantity Name of the unit of measurement Symbol of the unit of measurement Areasquare meterm2m2 Volumecubic meterm3m3 Densitykilogram per cubic meterkg/m 3 Forcenewton N (kg  m/s 2 ) Pressurepascal Pa (N/m 2 ) Energy, workjoule J (N  m) Speedmeter per secondm/s © Zanichelli editore 2015 Out of the combination of the base quantities it is possible to derive many other quantities.

Multiple of the units of measurement 14 Submultiple PrefixSymbol pico-p nano-n micro-μ milli-m centi-c deci-d- Multiple PrefixSymbol 10deca-da hecto-h kilo-k mega-M giga-G tera-T- © Zanichelli editore 2015

Scientific notation 15 Scientific notation expresses numerical data as the product of a number and a power of 10. The diameter of the Earth is around m, that is 12  10 6 m. © Zanichelli editore 2015

Extensive and intensive quantities 16 Extensive quantities vary as the size of the body under examination changes. Intensive quantities do not depend on the size of the body under examination. Mass and volume are extensive quantities. Temperature and density are intensive quantities. © Zanichelli editore 2015

The mass depends on the quantity of matter 17 The mass (m) of a body expresses its inertia. It is measured in kilograms (kg). The mass only depends on the quantity of matter of the body. © Zanichelli editore 2015

Weight and mass /1 18 The weight (W) should not be confused with the mass. The weight of a body with mass m is the force of gravity (g) on the body, according to the relation W = m  g. The unit of measurement is the newton (N). © Zanichelli editore 2015

Weight and mass /2 19 The force of gravity can vary in different points on the Earth and on different planets or celestial bodies. The same body with mass m can therefore have different weights in different conditions. Planet Gravitational acceleration (m/s 2 ) Mercury3.7 Venus8.85 Earth9.81 Moon1.62 Mars3.72 Jupiter26.39 Saturn11.67 Unanus11.48 Neptune11.97 © Zanichelli editore 2015

Volume of a body can change 20 Volume (V) is the space occupied by a body. It is expressed in cubic meters (m 3 ) or in liters (L). With the use of standard containers it is possible to measure volume of liquids, solids and gasses. © Zanichelli editore 2015

Density depends on body composition /1 21 Density (d) is the relationship between the mass and volume of a body (d = m/V). It is expressed in kg/m 3. Density varies according to the material, the temperature and the physical state. © Zanichelli editore 2015

Density depends on body composition /2 22 Solids and liquids Density (g/cm 3 at 20 °C) Ethanol0.79 Olive oil0.92 Water (at 4 °C)1 Sugar1.59 Mercury13.58 Gold19.32 Gasses Density (g/dm 3 at 0 °C) Hydrogen0.09 Methane0.72 Nitrogen1,25 Air1.29 Oxygen1.43 Carbon dioxide1.98 © Zanichelli editore 2015

Energy exchange between bodies and environment 23 Energy (E) is the ability to do work or produce light and heat. It can manifest itself in different forms and it can be lost or acquired by a body. The unit of measurement is the joule (J). © Zanichelli editore 2015

Different forms of energy 24 Kinetic energy is associated with the movement of a body. Potential energy depends on the composition or position of a body. Chemical energy is a type of potential energy like the gravitational energy of water in a dam. © Zanichelli editore 2015

Temperature measures the thermal state of a body 25 Temperature is the quantity that expresses the thermal state of a body, which is its ability to exchange heat. The SI unit of measurement is the Kelvin (K): T (K) = t (°C) + 273,15 Celsius scale Kelvin scale © Zanichelli editore 2015

Heat: energy in transit 26 Heat is thermal energy that is transferred from a body at a higher temperature to a body at a lower temperature. © Zanichelli editore 2015