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.
Answer:
p>Whether an object will float or sink is dependent on its density, and on the density of the liquid it is placed in. In the case of water, an object with a density less than 1 g/cm3 will float. The closer its density is to 1 g/cm3, the more of it will sit below the water level.
Answer:
The amount of time is 31.45 sec.
Explanation:
Given that,
Voltage = 10.0 V
Resistance
Capacitance
We need to calculate the time constant
Using formula of time constant
Put the value into the formula
The amount of time required for the current in the circuit to decay to 4.00% of its original value.
We need to calculate the amount of time
Using formula of charge
Put the value into the formula
Hence, The amount of time is 31.45 sec.
Answer:
Ohm's law: I = V / R
Explanation:
V, I, and R, the parameters of Ohm's law
with
V = voltage in Volt
I = current in Ampere
R = resistance in Ohm
Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality.
The following equation is known as Ohm's law:
I = V / R
You can also write Ohm's law as
V = I * R
You can also write Ohm's law as
R = V / I
Ohm's law states that the R in this relation is constant, independent of the current