Answer:
11460 years
Explanation:
Let N₀ be the initial amount of carbon present. After one half-life, its value is N₀/2, after two half-lives, it is N₀/4 = N₀/2². After n nalf-lives, it is N = N₀/2ⁿ.
Now, if the value of carbon-14 drops to a quarter of its initial value, then N = N₀/4.
So, N₀/4 = N₀/2ⁿ
1/4 = 1/2ⁿ
1/2² = 1/2ⁿ
Comparing the exponents, n = 2.
So the value of carbon-14 present drops to a quarter of its initial value in 2 half-lives.
Since one-half life equals 5730 years, then two-half-lives is 2 × 5730 years = 11460 years
So, it takes carbon-14 11460 years for the number of nuclei to drop to a quarter of its initial value.
Answer:
3rd answer
Explanation:
compare the total amount of time for each student
It is the last number minus 3
Answer: 0.42 km/min
Explanation:
total distance traveled(in meters) = 210m
total distance traveled(in km) = 210 ÷ 1000 = 0.21 km
total time taken(in seconds) = 30 s
total time taken(in minutes) = 30 ÷ 60 = 0.5 s
speed =(distance traveled)÷(time taken)[in km/min] = 0.21 ÷ 0.5 = 0.42km/min