Brawley Middle Sixth Grade Science Forces and Motion Christophe Fatton

Objective 1 Can Explain Wave properties and behaviors Can compare the properties of waves to the wavelike property of energy in earthquakes Can compare the properties of waves to the wavelike property of energy in light Can compare the properties of waves to the wavelike property of energy in sound

Forces and Motion Definition of force: strength or energy as an attribute of physical action or movement Forces move a medium up and down or back and forth A wave moves forward

Wave is a Disturbance Definition of Wave: disturbance that transfers energy from one place to another. Waves can transfer energy over distance without moving matter the entire distance. Ocean wave can travel many kilometers without the water itself moving many kilometers.

Potential & Kinetic Energy Potential Energy: the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors. Kinetic Energy: energy that a body possesses by virtue of being in motion.

Materials and Waves Medium: any substance that a wave moves through. Water is medium for ocean waves The ground is medium for earthquake wave Rope is medium for rope wave Mechanical Waves: waves that transfer energy through matter.

Wave’s Movement Transverse wave: The direction in which the wave travels in perpendicular, or at right angles, to the direction of the disturbance. “across” or “crosswise”

Wave’s Movement Longitudinal Waves: wave travels in the same direction as the disturbance. Can sometimes called compressional waves because the bunched-up area. Example: sound waves

Longitudinal vs. Transvers Waves

Measuring Wave Properties Crest: the highest point, or peak, of a wave. Trough: the lowest point, or valley, of a wave.

Three properties of a wave that can be measured. Amplitude For transverse waves: distance between a line through the middle of a wave and a crest or through. For an ocean wave: how far the wave rises above or dips below, its original position, or rest position. Wavelength: measure from trough to trough Frequency: Number of waves passing a fixed point in a certain amount of time.

Amplitude, Wavelength, and Frequency

Speed of Wave Definition: speed at which waves travel and is equal to wavelength x frequency.

Waves Interact with Materials Reflection: bouncing back of a wave after it strikes a barrier.

Waves Interact with Materials Refraction: bending of a wave as it enters a new medium at an angle other than 90 degrees. It occurs because waves travel at different speeds in different mediums.

Waves Interact with Materials Diffraction: spreading out of waves through an opening or around the edge of an obstacle.

Waves Interact with Materials Interference: the meeting and combining of waves

Waves in Earthquakes Earthquake: shaking of the ground cause by the sudden movement of large blocks of rock along a fault.

Earthquake’s Waves Seismic waves: an elastic wave in the earth produced by an earthquake or other means. Example: Ripple of waves when one throw a rock into a pond.

Types of Seismic Waves Primary Waves(P): The fastest seismic waves. First to reach any particular location after an earthquake occurs. Travels about 5 kilometers per second ( 3mi/s ) Can travel through solids, liquids, and gases. Push and pull – type of movement Secondary Waves ( S): secondary waves that arrive at any particular location after an earthquake. Starts at same time as primary waves Shake up and down or from side to side – movement Can travel through rocks but not liquids or gases That’s how we know the center of earth is not solid. Surface Waves: Seismic waves that move along earth’s surface, not through its interior. Roll up and down or shake from side to side. Cause largest ground movements and the most damage. More slowly than the other types of seismic waves

Seismic Waves

Properties of light Wave Electromagnetic Wave: Disturbance that transfers energy through a field. Wave that does not need a medium in which to travel. Can travel in a vacuum, air, water, and glass.

Electromagnetic waves

Light waves Light waves travel as transverse waves

How light Travels Through the Human Eye. Human eye: natural optical tools that process visible light. Transmit light, refract light, and respond to different wavelengths of light. Contains natural lenses that focus images of objects Convert energy of light waves signals as shape, brightness, and color.

Human Eye Cornea: Light enters the eye through the cornea , a transparent membrane that covers the eye. Pupil: Light then continues through the pupil, a circular opening that controls how much light enters the eyes. It is surrounded by the iris, which opens and closes to change the size of the pupil. Lens: light passes through the lens. It refracts light to make fine adjustments for near and far objects. Retina: Light passes through the clear center of the eye and strikes the retina. It contains specialize cells that respond to light, and detect brightness and color and other qualities of light. Rod cells- distinguish between white and black and shades of gray. Respond to faint light that help with night vision Cone cells- Respond to different wavelengths of light, so they detect color. Red, blue, and green are the three types of cones.

Light Waves Reflection: Process of light striking an object and bouncing off. We can read a book because light is reflecting from the page and into our eyes.

Sound Waves Sound: wave that is produce by a vibrating object and travels through matter. Vibration: the disturbances that travels in sound. Vibration is a rapid, back-and-forth motion. Sound waves are longitudinal waves. Sound waves also transfer energy through a medium.

Sound Waves We have sound making instrument within our own body. They are voice box, or larynx. Muscles push air up from your lungs and through the narrow opening between the vocal cords. Force of the air causes the vocal cords to vibrate Vibrating vocal cords produce sound waves

How Sound Waves Are Produce We have sound making instrument within our own body. It is voice box, or larynx. Human Voice Muscles push air up from your lungs and through the narrow opening between the vocal cords. Force of the air causes the vocal cords to vibrate Vibrating vocal cords produce sound waves

How Sound Waves Are Detected The shape of a human ear helps collect sound waves. Human Ear Sound waves cause the eardrum to vibrate. The vibrations travel through the hummer, anvil, and stirrup to the inner ear. Cells in the cochlea detect the vibrations and send a message to brain.