<span> In radioactive decay, an unstable atomic nucleus emits particles or radiation and converts to a different atomic nucleus. If the new nucleus is unstable, it will decay again, until eventually, a stable nucleus is formed. Such a sequence of nuclear decays forms a decay series.
The half-life of a radioactive substance is the time required for half of the atoms of a radioactive isotope to decay. If you have, say, 1 million atoms of a specific isotope in a sample, the time required for 500,000 of those atoms to decay is the half-life of that specific isotope. If you have 50 atoms of that isotope, 25 atoms will decay in the same amount of time.
Because the half-life is fixed for a specific isotope, it can be used to date objects. You compare the decay rate of an old object with the decay rate of a fresh sample. Nuclear decay is a first-order process and can be described by a specific mathematical equation, which depends on the decay rate and the half-life. Knowing those values, you can work back and determine the age of an object, as compared with a standard sample. Old objects will not have as much of a radioactive isotope in them as new objects, since the isotopes will have decayed over time in the old object.</span>
Greenhouse Gases, on relation to Earth's atmosphere.
A: w=mg w=13(9.8) w= 127.4
B: 13kg
C: w=mg w=13(1.6) w= 20.8
D: The force of gravity is less on the moon than on earth therefore making the dog weigh less.
<span>D. 80 degrees.
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The part of the ear where sound wave compressions and rarefactions cause the eardrum to vibrate is the middle ear. The 8th nerve in the inner ear actually converts the mechanical energy to electrical energy for transmitting to the brain. A membrane called the tympanic membrane separates the middle ear from the outer ear. Whenever a sound reaches the ear, it creates a sound wave that creates vibration in the eardrum. The pressure when high pushes the membrane inwards while low pressure sound waves helps the eardrum to come outwards.
Answer:
For cardboard = 29.4 g/cm²
For aluminium = 113.4 g/cm²
For lead = 193.8 g/cm²
Explanation:
Given:
Density of the cardboard, d₁ = 0.6 g/cm³
Density of the aluminium, d₂ = 2.7 g/cm³
Density of the lead, d₃ = 11.4 g/cm³
Length of the cardboard, L₁ = 49 cm
Length of the aluminium, L₂ = 42 cm
Length of the lead, L₃ = 17 cm
Now,
The absorber thickness is calculated as:
= Density × Length
therefore,
For cardboard = d₁ × L₁ = 0.6 × 49 = 29.4 g/cm²
For aluminium = d₂ × L₂ = 2.7 × 42 = 113.4 g/cm²
For lead = d₃ × L₃ = 11.4 × 17 = 193.8 g/cm²
