Fundamental Physics: Sound, Radioactivity, Planets & Gravity

Sound Questions from Exam #2

How does the density of the medium affect the speed of sound? The density of a medium is the second factor that affects the speed of sound; the greater the density, the faster the sound.

• b) Which is the softest sound a human can hear? 20 Hz… 0 dB
• c) What is an example of a sound which will cause immediate hearing loss? Jet engine. dB range for this sound: 120 dB
• d) Two sounds are emitted at the same time: Sound A: 10 meters through air, Sound B: 10 meters through water: which travels faster? Sound B
• e) In the dB or decibel scale, sound pressure is compared to: The softest a human can hear.

Solar System Planet Order

Solar system in order distance of planets from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Why is Mars most likely to have a life? Mars' climate is most like Earth and it has the most similarities to Earth too. It was thought to have water, which is basic for life.

Decay (From Exam #2)

5 kinds of radioactive decay and the effect on the number of protons and neutrons in the nucleus: 3 major types of nuclear decay: alpha emission -2, beta emission -1, gamma emission 0. Each type emits a particle from the nucleus. Alpha particles are high-energy helium nuclei containing 2 protons and 2 neutrons. — Electron Capture and Positron Emission: change in neutron number: +1

• Gamma Decay: Number of protons and number of neutrons unchanged.
• Alpha Decay: Number of protons decreases, and neutrons decreases.
• Beta Decay: Number of neutrons decrease, number of protons increases.
• Positron Emission: Number of neutrons increased, protons decreased.
• Electron Capture: Number of neutrons increase, protons increase.

Gravity and Time Dilation

Gravity: Time is faster at high altitude. "Time-dilation" effect is a consequence of Einstein's theory of general relativity, which posits that the gravity of a massive body — such as the Earth — warps the space-time around it, causing the flow of time to speed up or slow down depending on its distance from the mass. Gravity is (or gravitation), a natural phenomenon by which all things with mass are brought toward (or gravitate toward) one another.