Physical Science and You

• Chapter One: Studying Physics and Chemistry

• Chapter Two: Experiments and Variables

• Chapter Three: Key Concepts in Physical Science

Chapter Three: Key Concepts in Physical Science

• 3.1 Mass and the Atomic Theory of Matter

• 3.2 Temperature and Energy

Investigation 3B

• How do scientists measure things too small to put on a balance?

Mass and Indirect Measurement

How do we measure tiny objects such as a single grain of rice?

3.2 Systems

• In science, the word “system” means a group of related things that work together.

What part in our optical system controls the amount of light entering the eye?

3.2 Energy

• The parts of a system interact with each other by exchanging energy.

Where does our eye get the energy it needs to open or close the pupil?

3.2 Energy• Energy causes change.• Some changes that occur in systems

include:1. temperature2. speed3. position4. mass5. other physical variables

What changes can take place in this system?

3.2 Force

• Force is a fundamental quantity in physical science.

• In the metric system, force is measured in newtons (N).

Would more or less force be needed to pull 2 books?

3.2 Energy

• The unit of energy is related to the units for force and distance.

• One joule (J) of energy is enough to pull with a force of one newton for a distance of one meter.

3.2 Potential Energy

• Some objects may have energy due to their height.

• This kind of energy is called potential energy and comes from Earth’s gravity.

3.2 Kinetic Energy

• Objects in motion have energy due to their speed.

• Energy of motion is called kinetic energy.

3.2 Temperature

• Temperature is the measurement we use to make the sensations of hot and cold more precise.

• A thermometer is an instrument used to accurately measure temperature.

3.2 Fahrenheit

• Gabriel Fahrenheit, a German physicist, was the first person to use a mercury thermometer.

• The Fahrenheit scale was standardized so that the freezing point of water is 32 degrees and the boiling point is 212 degrees.

3.2 Celsius

• Anders Celsius, a Swedish astronomer, invented a temperature scale in which there were 100 degrees between freezing and boiling.

3.2 Extreme Temperatures

• Absolute zero is -273°C. • You cannot have a temperature lower than

absolute zero.• Think of absolute zero as the temperature

at which atoms are “frozen.”

3.2 Extreme Temperatures

• Scientists experiment with temperatures as low as billionths of a degree above absolute zero and as high as 100 million million degrees Celsius.

3.2 Heat and thermal energy

• Temperature measures a kind of energy called thermal energy.

• Thermal energy comes from the motion of atoms in matter.

• We call thermal energy that is flowing heat.

3.2 Heat and thermal energy

• Thermal energy is often measured in calories.

• One calorie is the amount of energy it takes to raise the temperature of one milliliter of water by one degree Celsius.

3.2 Specific heat• The specific heat is a

property of a substance that tells us how much heat is needed to raise the temperature of one kilogram of a material by one degree Celsius.

Knowing the specific heat of a material tells you how quickly the temperature will change as it gains or loses energy.

3.2 Conservation of Energy

• The law of conservation of energy says that energy can never be created or destroyed, just converted from one form into another.

• The law of conservation of energy applies to all forms of energy.

3.2 “Conserving” Energy

• Electric power plants do not make electrical energy.

• Power plants convert other forms of energy (chemical, solar, nuclear) into usable electrical energy.We may be running out

of certain “forms” of energy that are easy or inexpensive to use.

Activity

• Working together, brainstorm what question your group would like to find answers to.

• Choose from the materials pictured.

Your Own Science Experiment