Answer:
A half-life is the time required for one half of the nuclei in a radio- active isotope to decay.
Explanation:
A radio-active isotope is an isotope which undergoes radioactive decay.
Radioactive decay is a spontaneous process in which the nucleus of an atom changes its state (turning into a different nucleus, or de-exciting), emitting radiation, which can be of three different types: alpha, beta or gamma.
The half-life of a radio-active isotope is the time required for half of the nuclei of the initial sample to decay.
The law of radio-active decay can be expressed as follows:
where
N(t) is the number of undecayed nuclei left at time t
N0 is the initial number of nuclei
t is the time
is the half-life
We see that when 
(that means, when 1 half-life has passed), the number of undecayed nuclei left is
So, half of the initial nuclei.
Answer:
q = 8.57 10⁻⁵ mC
Explanation:
For this exercise let's use Newton's second law
F = ma
where force is magnetic force
F = q v x B
the bold are vectors, if we write the module of this expression we have
F = qv B sin θ
as the particle moves perpendicular to the field, the angle is θ= 90º
F = q vB
the acceleration of the particle is centripetal
a = v² / r
we substitute
qvB = m v² / r
qBr = m v
q =
The exercise indicates the time it takes in the route that is carried out with constant speed, therefore we can use
v = d / t
the distance is ¼ of the circle,
d = 
d =
we substitute
v = 
r = 
let's calculate
r =
2 2.2 10-3 88 /πpi
r = 123.25 m
let's substitute the values
q = 
7.2 10-8 88 / 0.6 123.25
q = 8.57 10⁻⁸ C
Let's reduce to mC
q = 8.57 10⁻⁸ C (10³ mC / 1C)
q = 8.57 10⁻⁵ mC
It should be Constant speed. The line goes straight & doesn’t change within the graph.
Answer:
1.21m
Explanation:
If two speakers are generating a frequency of 280Hz, the smallest separation distance between the speakers that will produce destructive interference at a listener standing in front of them is also known as the wavelength of the sound wave generated.
Using the expression;
Velocity v = frequency f × wavelength ¶
Given frequency = 280Hz, speed of sound v = 338m/s
Substituting this data's in the expression given to get the wavelength will give;
¶ = v/f
¶ = 338/280
¶ = 1.21m
The smallest separation between the speakers that will produce the interference is 1.21m
Answer:
Then the difference of weight between the two cars are:
Δw = 14210 - 5292 = 8918 N
Explanation:
An object's weigh due to the gravitational attraction force of the earth is:
w = mg
Where: m is the object's mass
g is the gravitational acceleration in the surface earth
g = 9.8 m/s2
The the ultralight car's weight is:
And the Honda Accord's weight is:
Then the difference of weight between the two cars are:
Δw = 14210 - 5292 = 8918 N
