s6 Waves Energy and Vibrations
Waves and Energy
A wave is a disturbance that transfers energy from place to place. In science, energy is defined as the ability to do work. To understand waves, think about the swimming raft. A wave that disturbs the surface of the water also will disturb the raft. The wave’s energy lifts the heavy raft as the wave passes under it. But the disturbance caused by the wave is temporary. After the wave passes, the water is calm again and the raft stops bobbing.
What Carries Waves?
Most kinds of waves need something to travel through. Sound waves travel through air. Water waves travel along the surface of the water. A wave can even travel along a rope. The material through which a wave travels is called a medium. Gases (such as air), liquids (such as water), and solids (such as rope) all act as mediums. Waves that require a medium through which to travel are called mechanical waves.
But not all waves require a medium to travel through. Light from the sun, for example, can carry energy through empty space. If light could not travel through empty space, you could not even see the sun! Waves that can travel without a medium are called electromagnetic waves. You will learn more about electromagnetic waves in a later chapter.
How Do Waves Transfer Energy?
Although mechanical waves travel through a medium, they do not carry the medium with them. Look at the duck in Figure 1. When a wave travels under the duck, the duck moves up and down. But the duck does not travel with the wave. After the wave passes, the duck and the water return to where they started.
Why doesn’t the medium travel along with the wave? All mediums are made of tiny particles. When a wave enters a medium, it transfers energy to the medium’s particles. The particles bump into each other, passing the wave’s energy along. To understand this, think about how food is passed at a table. You hand the food to the next person, who passes it to the next person, and so on. The food is transferred, but the people don’t move. The food is like the wave’s energy, and the people are like particles in a medium.
What Causes Waves?
Energy always is required to make a wave. Mechanical waves are produced when a source of energy causes a medium to vibrate. A vibration is a repeated back-and-forth or up-and-down motion. When a vibration moves through a medium, a wave results.
Moving objects have energy. A moving object can transfer energy to a medium, producing waves. For example, you can make waves by dipping your finger in water. Your finger has energy because it is moving. When your finger touches the water, it transfers energy to the water and makes waves. In the same way, a motorboat slicing through calm water transfers energy to the water and makes waves.
What is a Vibration?
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A wave is a disturbance that transfers energy from place to place. In science, energy is defined as the ability to do work. To understand waves, think about the swimming raft. A wave that disturbs the surface of the water also will disturb the raft. The wave’s energy lifts the heavy raft as the wave passes under it. But the disturbance caused by the wave is temporary. After the wave passes, the water is calm again and the raft stops bobbing.
What Carries Waves?
Most kinds of waves need something to travel through. Sound waves travel through air. Water waves travel along the surface of the water. A wave can even travel along a rope. The material through which a wave travels is called a medium. Gases (such as air), liquids (such as water), and solids (such as rope) all act as mediums. Waves that require a medium through which to travel are called mechanical waves.
But not all waves require a medium to travel through. Light from the sun, for example, can carry energy through empty space. If light could not travel through empty space, you could not even see the sun! Waves that can travel without a medium are called electromagnetic waves. You will learn more about electromagnetic waves in a later chapter.
How Do Waves Transfer Energy?
Although mechanical waves travel through a medium, they do not carry the medium with them. Look at the duck in Figure 1. When a wave travels under the duck, the duck moves up and down. But the duck does not travel with the wave. After the wave passes, the duck and the water return to where they started.
Why doesn’t the medium travel along with the wave? All mediums are made of tiny particles. When a wave enters a medium, it transfers energy to the medium’s particles. The particles bump into each other, passing the wave’s energy along. To understand this, think about how food is passed at a table. You hand the food to the next person, who passes it to the next person, and so on. The food is transferred, but the people don’t move. The food is like the wave’s energy, and the people are like particles in a medium.
What Causes Waves?
Energy always is required to make a wave. Mechanical waves are produced when a source of energy causes a medium to vibrate. A vibration is a repeated back-and-forth or up-and-down motion. When a vibration moves through a medium, a wave results.
Moving objects have energy. A moving object can transfer energy to a medium, producing waves. For example, you can make waves by dipping your finger in water. Your finger has energy because it is moving. When your finger touches the water, it transfers energy to the water and makes waves. In the same way, a motorboat slicing through calm water transfers energy to the water and makes waves.
What is a Vibration?
.
What Causes Waves?
Energy always is required to make a wave. Mechanical waves are produced when a source of energy causes a medium to vibrate. A vibration is a repeated back-and-forth or up-and-down motion. When a vibration moves through a medium, a wave results.
Moving objects have energy. A moving object can transfer energy to a medium, producing waves. For example, you can make waves by dipping your finger in water. Your finger has energy because it is moving. When your finger touches the water, it transfers energy to the water and makes waves. In the same way, a motorboat slicing through calm water transfers energy to the water and makes waves.
Energy always is required to make a wave. Mechanical waves are produced when a source of energy causes a medium to vibrate. A vibration is a repeated back-and-forth or up-and-down motion. When a vibration moves through a medium, a wave results.
Moving objects have energy. A moving object can transfer energy to a medium, producing waves. For example, you can make waves by dipping your finger in water. Your finger has energy because it is moving. When your finger touches the water, it transfers energy to the water and makes waves. In the same way, a motorboat slicing through calm water transfers energy to the water and makes waves.
