Answer:
Explanation:
The <em>half-life </em>of a radioisotope, in this case carbon-14, is the time that a sample requires to reduce its amount to half, and it is a constant for every radioisotope (it does not change with the amount of sample).
Then, the formula for the remaining amount of a radioisotope is:
Where:
- A is the final amount of the element,
- A₀ is the initial amount of the element,
- A/A₀ is ratio of remaining amount to the original amount, and
- n is the number of half-lives elapsed
The number of half-lives for carbon-14 elapsed for the dinosaur fossil is:
- n = 68 million years / 5730 years ≈ 11,867
Then, A / A₀ = (1/2)ⁿ = (1/2)¹¹⁸⁶⁷ ≈ 0.00000 .
The number is too small, and when you round to five decimal places the result is zero. That is why carbon-14 cannot be used to date dinosaur fossils, given that they are too old.
Explanation:
(c) I assume we're looking for mA.
Sum of forces on B in the -y direction:
∑F = ma
mBg − T = mBa
Sum of forces on A in the +x direction:
∑F = ma
T = mAa
Substitute:
mBg − mAa = mBa
mBg − mBa = mAa
mA = mB (g − a) / a
Plug in values:
mA = (5 kg) (10 m/s² − 0.01 (10 m/s²)) / (0.01 (10 m/s²))
mA = 495 kg
The answer key seems to have a mistake. It's possible they meant mB = 1 kg, or they changed mB to 5 kg but forgot to change the answer.
Electromagnetic transverse waves
Answer: Terminal velocity is achieved, therefore, when the speed of a moving object is no longer increasing or decreasing; the object's acceleration (or deceleration) is zero.
Explanation:.