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Answer:
Characteristic time τ=20 s
When V = 15 m/s
t = 6.66 s
When V = 10 m/s
t = 20 s
When V = 5 m/s
t = 60 s
Explanation:
Given that
c=0.20 N/m(m/s)2
m = 80 kg
Vo=20m/s
Characteristic time τ=m/cvo.
Characteristic time τ=20 s
We know that velocity after t time given as follows
When V = 15 m/s
t = 6.66 s
When V = 10 m/s
t = 20 s
When V = 5 m/s
t = 60 s
Answer:
Tectonic Plate Movement
Explanation:
Each continent and ocean sits on its own tectonic plate which floats on the Earths upper mantle. They move very little over time.
1) The half-life is the time required for a substance to reduce to half its initial value. In formulas:
(1)
where
m(t) is the amount of substance left at time t
m0 is the initial mass
is the half-life
In this problem, the half-life of the substance is 20 years:
therefore, the fraction of sample left after t=40 years will be
So, only 1/4 of the original sample will be left, which corresponds to 25%.
2) We can use again formula (1), by re-arranging it:
If we use m(t)=10 g (mass of uranium left at time t), and
(the time is equal to 4 half lifes), we get
So, the initial sample of uranium was 160 g.