Sounds & Stuff

• What is sound made from?

  Sound is made when objects vibrate.
• How is loudness described?

  Loudness describes how loud or quiet a sound appears.
• What two variables does loudness depend on?

  Loudness depends on how much the object is vibrating and how far away the vibrating object is.
• What is the peak of a wave?

  The peak is the highest point of the wave from zero to top.
• What is the trough of a wave?

  The trough is the lowest point of the wave from zero to bottom.
• What does amplitude measure in a sound wave?

  Amplitude measures the maximum distance that particles move in a sound wave.
• How does amplitude relate to loudness?

  A higher amplitude results in a louder sound, while a lower amplitude results in a quieter sound.
• What is pitch in terms of sound?

  Pitch describes how high or low the sound appears on a musical scale.
• What does pitch depend on?

  Pitch depends on the speed of vibrations per second.
• What is frequency in sound?

  Frequency is the number of vibrations per second measured in hertz (Hz).
• What does a frequency of 500 Hz indicate?

  A frequency of 500 Hz means that 500 complete vibrations happen every second.
• What happens to amplitude as frequency increases?

  As frequency increases, the amplitude also increases.
• What is interference in sound waves?

  Interference is the effect produced when two waves meet each other.
• When is interference easiest to detect?

  Interference is easiest to detect when the waves have the same frequency and amplitude.
• What are the two effects produced by interference of waves?

  The waves can reinforce each other or cancel each other out.
• What happens when sound waves reinforce each other?

  When sound waves reinforce, the amplitude increases but the frequency stays the same.
• What is required for two sound waves to reinforce?

  For two sounds to reinforce, they must have the same frequency.
• What is required for two sound waves to cancel each other?

  For two sound waves to cancel, they need to have the same frequency and amplitude, but in opposite directions.
• What was the 20th-century theory about the Moon's formation?

  Scientists thought the Moon was formed by splitting away from the Earth.
• What does the Moon's movement indicate if the splitting theory is correct?

  If the splitting theory is correct, the Moon is still moving away from the Earth at about 4 cm each year.
• What does the collision theory refer to?

  The collision theory refers to a collision that happened soon after the formation of the solar system.
• What was the newly formed planet involved in the collision theory?

  The newly formed planet called Theia collided with the newly formed Earth.
• What was the result of the collision between Theia and Earth?

  The collision caused rocks and dust to break away from both planets, forming the Moon.
• What is one piece of evidence supporting the collision theory?

  The Moon is less dense than Earth.
• What do rock samples from the Moon indicate?

  Samples of rock from the Moon show that its surface was once molten.
• What is a characteristic of the Moon's core?

  The Moon has a small iron core, similar to Earth.
• What evidence exists outside the Solar System related to the collision theory?

  There is evidence of similar collisions causing rings of rocks and dust.
• How does the collision theory fit with the solar system formation theory?

  The collision theory fits with the theory of how the solar system was formed.
• What is a similarity between the rocks on Earth and the Moon?

  The composition of rocks on Earth and the Moon are the same.
• What is one piece of evidence that contradicts the collision theory?

  The surface of the Earth does not appear to have been molten after the collision.
• What is another piece of evidence that contradicts the collision theory?

  Venus has no moon, which contradicts the expectation of common collisions.
• What is a third piece of evidence that contradicts the collision theory?

  The composition of rocks on the Moon would be expected to be more similar to Theia than to Earth rocks.
• What are nebulae?

  Nebulae are clouds of dust and gas in space.
• What is the singular form of nebulae?

  The singular form of nebulae is nebula.
• What gases are mostly found in nebulae?

  The gases found in nebulae are mostly hydrogen and a smaller quantity of helium.
• How are some nebulae formed?

  Some nebulae are formed when giant stars explode and send dust and gas over a wide area of space.
• Name two nebulae visible to the naked eye.

  The Orion nebula and the Carina nebula.
• What is a stellar nursery?

  A stellar nursery is an area in space where stars are formed.
• How is a star born in a stellar nursery?

  A star is born when dust and gas collapse under gravity, increasing pressure and causing heat.
• What does the pressure inside a new star cause?

  The pressure causes heat, which causes atoms to react and the new star to give out heat and light.