Physical Science Chapter 16 Grade 5

Chapter 16- Energy and Waves

Lesson 1- Kinetic and Potential Energy ► Forms of Energy  Energy is the ability to do work ► Measured in Joules ► Energy comes in different forms such as: Thermal, chemical, electromagnetic, electrical and mechanical

► Thermal Energy- is the motion of the particles in matter, felt as heat ► Electromagnetic energy is visible light, microwaves, radio waves and X-rays ► Chemical Energy- can be released during a chemical reaction, like burning coal, or a battery in a toy car. ► Electricity – movement of charges particles. Powers almost everything in your house. ► Mechanical Energy- energy an object has because of its motion or position  Wind, sound, or falling objects

Answer this: ► If a Large Rock is on the edge of a cliff, what kind of energy does it have?

Answer ► Potential Mechanical Energy

Kinetic Energy ► Kinetic Energy- energy of movement. ► Any moving object has kinetic energy  A bowling ball rolling down an alley  Falling rock  Vibrating object

Potential Energy ► The energy an object has stored is Potential energy.  Rock on a ledge  Compressed spring  Rubber band being held

► When work is done, energy transfers from one form to another ► Example: An archer pulls back the bow and arrow. The bent bow has stored POTENTIAL energy. When it is released, the energy is changed to Kinetic, mechanical energy.

Calculating Mechanical Energy ► When an object with Potential energy starts to move, some of that energy is changed to Kinetic energy ► As the amount of Kinetic energy increases, Potential energy decreases ► Mechanical Energy- is the SUM of PE and KE  In a falling object, PE and KE will change, but ME will stay the same.

Lesson 2- How Are Sounds Made

Sound Production ► A mechanical wave forms when energy moves through a medium or matter. ► Transverse Waves move perpendicular to the direction of the wave  Waves in a jump rope ► Longitudinal Waves move parallel to the direction of the wave  A slinky moving back and forth,  Where particles come together they form compressions

Waves ► Waves are measured by two things: ► Amplitude- how high a wave is from crest to trough, (top to bottom) ► Wavelength- the distance between two waves ► Scientists also measure frequency, or how many waves pass per second  Shorter wavelengths have higher frequencies  Longer wavelengths have lower frenquencies

Sound Waves ► Sound waves are produced through vibrations  The energy of the vibrations travels through the medium as a longitudinal wave. ► Waves travel at different speeds through different materials.  Metals vibrate more easily than rubber. Ex: Tuning forks  Sound waves move faster through solids and liquids than through gases

Pitch ► The properties of sound depend on the vibrations produced ► Pitch is how high or low you perceive an object to be  Depends on the wave’s frequency  Higher frequency, higher pitch (whistle)  Lower frequency, lower pitch (tuba)

Volume ► Volume- strength of a vibration causing a sound to be loud or soft ► Sound is measured in decibels

Acoustics ► Sound waves can behave differently when they hit different materials ► Acoustics is the study of how materials affect sound waves  A sound wave will reflect off hard surfaces ► Grand Canyon echoes  Sound waves are absorbed by most soft or porous surfaces ► Cotton and other materials in recording rooms

Lesson 3- Properties of Light

Electromagnetic Waves ► Light Waves are electromagnetic waves  Can travel through a medium or vacuum  Examples include: x-rays, gamma rays, UV rays, visible light ► Different EM waves have different frequencies and wavelengths ► Visible light is seen by humans  Consists of seven different colors

► Some waves can be harmful to living things ► EM waves interact differently with different materials  Some materials will reflect certain wavelengths of color, and absorb others.  Example: Apple reflects red and absorbs other colors

Reflection and Refraction ► Light can be absorbed, reflected or refracted as it hits an object ► Reflection occurs when a wave bounced off a material  Ex: looking in a mirror ► Refraction- when the path of light changes from one material to the next  Ex: a pencil looking “broken” in a glass of water

► A convex lens beds light rays toward one another. ► A concave lens bends light rays away from one another. ► People with glasses use different lenses to refocus light and images onto the retina

Fiber Optics ► Fiber optics use total internal reflection  Has helped to improve communication systems and medical procedures  Optical fibers can transmit light over long distances