Answer:
t ≈ 5.1 days
Step-by-step explanation:
A 10 gram sample of a substance thats used to detect explosives has a k-value of 0.1356. Find the substances half-life in days. round your answer to the nearest tenth. N=N₀ e^-kt N₀= initial mass (at time t = 0) N = mass at time t k= a positive constant that depends on the substance itself and on the units used to measure time t=time in days
The initial condition is that, at time t = 0, the amount of substance contains originally 10 grams
Find the value of N₀
N=N₀ e^-kt
We substitute:
10 = N₀ {e^(-0.1356)*0}
10 = N₀ (e^0)
10=N₀(1)
10=N₀
N₀ = 10
When the substance is in half-life
That is, half of the original substance (5 grams)
Find t
N=N₀ e^-kt
5 = 10 e^(-0.1356*t)
0.5 = e^(-0.1356*t)
Bring down t by multiplying natural log on both sides
ln(0.5) = -0.1356*t
Divide both sides by -0.1356
t = -(ln(0.5) / 0.1356
t ≈ 5.11 days
To the nearest tenth
t ≈ 5.1 days
