Answer:
1694 days
Explanation:
In first-order kinetics, the rate is proportional to the amount.
dA/dt = kA
For first-order kinetics, the rate k can be found using the half-life:
t₁,₂ = (ln 2) / k
In other words, the half-life is inversely proportional with the rate.
At the lower temperature, the rate is reduced to a third, so the half-life increases by a factor of 3. Meaning that the new half-life is 170 × 3 = 510 days.
The "shelf life" is the time it takes to reduce the initial amount to 10%. We can solve for this using the half-life equation.
A = A₀ (½)^(t / t₁,₂)
A₀/10 = A₀ (½)^(t / 510)
1/10 = (½)^(t / 510)
ln(1/10) = (t / 510) ln(½)
ln(10) = (t / 510) ln(2)
ln(10) / ln(2) = t / 510
t = 510 ln(10) / ln(2)
t ≈ 1694
Answer:
48 m
Explanation:
As she travels at the rate of 5m/s due north, the amount of time it would take for her to cross the 80m wide river would be
t = 80 / 5 = 16 seconds
This is also the time it takes for the river to push her to the east side at the rate of 3m/s. So after 16 seconds, she would reach the opposite point at a horizontal distance from her starting of
s = 16*3 = 48 m
I believe it is called the Greenhouse effect.