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:
Number of turns in secondary is 20
Current in primary is 0.96 A
Explanation:
We have given number of turns in primary
Voltage across primary of transformer
Current in secondary coil
Voltage across secondary
For transformer we know that
So
So number of turns in primary is 20
Now
Current in primary of transformer is 0.96 A
The resistor's current I in amps is equal to the resistor's voltage V in volts (V) divided by the resistance R in ohms (Ω) I hope this helped
Answer:
0.00321 Nm
Explanation:
= Final angular velocity = 3.5 rad/s
= Initial angular velocity = 0
= Angular acceleration
= Angle of rotation = 2 rev
Equation of rotational motion
Moment of inertia is given by
Torque is given by
The torque required is 0.00321 Nm