Year 9 Science - Heat, Sound And Light

Sound is produced by vibrations. When an object vibrates, it creates sound waves that travel through the air or other mediums. These sound waves are detected by our ears, which then interpret them as sound. Therefore, it is true that sound is produced by vibrations.

Sound waves are longitudinal waves because they propagate by compressing and expanding the particles of the medium through which they travel. In a longitudinal wave, the particles of the medium vibrate parallel to the direction of wave propagation. This is exactly how sound waves behave, as they create areas of compression and rarefaction in the medium. Therefore, the statement that sound waves are longitudinal waves is true.

Sound waves are indeed longitudinal waves. This means that the particles of the medium through which the sound waves travel vibrate in the same direction as the wave is propagating. In other words, the particles move back and forth parallel to the direction of the wave. This is different from transverse waves, where the particles move perpendicular to the direction of the wave. Sound waves are created by the compression and rarefaction of air molecules, which causes a series of high and low pressure regions to propagate through the medium.

A cochlear implant is a medical device that is surgically implanted in the inner ear to help individuals with severe hearing loss or deafness. It works by converting sounds into electrical impulses that can stimulate the auditory nerve directly, bypassing the damaged parts of the ear. These electrical impulses are then sent to the brain, where they are interpreted as sound. Therefore, the statement that the cochlear implant converts sounds into electrical impulses that are sent to the brain is true.

Based on the given table, we can observe that the speed of sound varies in different materials. The materials with higher density, such as steel and glass, have higher speeds of sound compared to materials with lower density, such as air and water. Therefore, the correct answer is that sound travels faster through substances that are more dense.

The best insulator among the pool blankets tested is Silverline. This is because it was able to trap the most heat within the pool overnight, resulting in the highest water temperature of 26°C at 9 a.m. The other pool blankets, Hot stuff, Luxury liner, and Thermospecial, had lower water temperatures of 24°C, 25.5°C, and 23.5°C respectively. Therefore, Silverline demonstrated better insulation properties compared to the other pool blankets.

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Sound waves require a medium, such as air, water, or solids, to travel through. In a vacuum, there is no medium present, so sound waves cannot travel. Therefore, the statement that sound waves can travel in a vacuum is false.

The question asks to identify which of the two sounds have the same amplitude (loudness). In this case, sounds A and C have the same amplitude because they are at the same height on the graph, indicating that they have the same loudness. Sound B, on the other hand, has a different amplitude and is therefore not the same loudness as A and C.

The Kelvin is the standard SI unit for temperature and is used to measure absolute temperature. To convert Celsius to Kelvin, you add 273 to the temperature in degrees Celsius. In this case, to convert 35°C to Kelvin, you add 273, resulting in 308 K.

The sound with the highest frequency will have the shortest wavelength and will be perceived as a high-pitched sound. In the given options, sound C is represented as having the highest frequency.

Sound is a longitudinal wave, which means that the particles of the medium through which the sound wave travels vibrate back and forth in the same direction as the wave. This vibration of particles creates compressions and rarefactions, which are responsible for the propagation of sound. Therefore, the correct answer is that the particles vibrate back and forth.

The correct answer is: The sun transfers its heat energy through radiation, Conduction is when heat energy is transferred by vibrating particles, Convection is when heat energy diffuses through a liquid or a gas.

The video explains the different methods of heat transfer. It states that the sun transfers its heat energy through radiation, which is the transfer of heat through electromagnetic waves. Conduction is described as the transfer of heat energy through vibrating particles, where the particles pass the heat energy from one to another. Convection, on the other hand, is the transfer of heat energy through the movement of a liquid or a gas. Therefore, the correct answers are the ones that describe these different methods of heat transfer.

The semi-circular canals are responsible for our sense of balance. These fluid-filled structures in the inner ear detect changes in head position and movement, allowing us to maintain our equilibrium. When the head moves, the fluid inside the canals moves as well, stimulating hair cells that send signals to the brain, which then interprets these signals to maintain balance. The Eustachian tube helps equalize pressure in the middle ear, the oval window transmits sound vibrations, and the pinna collects sound waves, but they do not play a direct role in our sense of balance.

Different colours have different frequencies because each colour corresponds to a different wavelength of light. Red objects reflect red light because they absorb all other colours of light and only reflect red. Black objects absorb all colours of light, which is why they appear black.

The correct answer is "a parka, a woollen jumper, a cotton windcheater, a cotton T-shirt." This is because a parka is typically made of thick, insulated material that provides the most effective insulation. A woollen jumper is also made of a warm material and provides good insulation. A cotton windcheater is less effective than a woollen jumper but still provides some insulation. A cotton T-shirt is the least effective insulator as it is made of a lightweight and breathable material that does not provide much insulation.

The given answer choices accurately describe the concepts of sound production, frequency, pitch, and amplitude. Sound is produced when something vibrates, frequency refers to the number of waves passing a point each second, the higher the frequency the higher the pitch or tone of the sound, and amplitude refers to how loud the sound is.

The time delay between sending and receiving the ultrasound pulse can be calculated by dividing the distance traveled by the speed of sound in water. In this case, the distance traveled by the pulse is 750 meters, and the speed of sound in water is 1500 meters per second. Dividing 750 by 1500 gives us 0.5 seconds, which is the time it takes for the pulse to travel from the surface to the shark and back. Therefore, the correct answer is 1 second.

When a flute is played, the sound is produced by the different-sized columns of air inside the flute vibrating. As the player blows air into the flute, the air column inside the flute is divided into different sections by the keys and holes. When the player covers or uncovers these holes, it changes the length of the air column, causing it to vibrate at different frequencies. This vibration creates sound waves that produce the distinct tones and pitches of the flute. Therefore, it is the different-sized columns of air inside the flute that vibrate to produce the sound.

The correct answer options are all statements that accurately describe the process of hearing. Sounds are collected by the outer ear, the ear drum vibrates when sound waves strike it, the middle ear contains the hammer, anvil, and stirrup, the cochlear is filled with fluid, and the tiny hairs in the cochlear transform vibrations into electrical signals that go to the brain. These statements align with the information presented in the video.

The given answer is correct because it accurately identifies the following concepts:
1) Most of what we see is a reflection of light - This is true because objects reflect light and our eyes perceive that reflected light to see the objects.
2) Light sometimes acts like a wave - This is true because light exhibits wave-like properties such as interference and diffraction.
3) Light sometimes acts like a particle - This is also true because light can behave as discrete packets of energy called photons.