This is so frustrating I don’t even understand this
Answer:
= 72900 years
Explanation:
- The half-life is the time taken by a radioactive material to decay by half the original amount.
- The half-life of plutonium-239 is 24300 years which means it takes 24300 years to decay by half the original amount.
To calculate the time taken for a mass of 8 kg to decay to 1 kg we use;
New mass = Original mass x (1/2) ^n, where n is the number of half-lives
Therefore;
1 kg = 8 kg × (1/2)^n
1/8 = (1/2)^n
solving for n;
n =3
Therefore;
Time = 3 × 24300 years
= 72900 years
It will, therefore, take 72900 years for 8 kg of plutonium-239 to decay to 1 kg.
The net force = -5 N
The direction : to the left(negative sign)
<h3>Further explanation
</h3>
Net force : the sum of all forces acting on an object
Force is a vector quantity that has both magnitude and direction,
We agree that the move up and to the right is a positive sign, while down and to the left is a negative sign.
The direction of the force (horizontal motion) is to the right (+32 N), and to the left (-37 N), so the net force :
The formula for solving current given with resistance and power source or voltage is shown below:
I = V/R
When two 5 ohms resistors are in series, we have:
I = 9 volts / (5+5 ohms)
I = 0.9 amperes
When it is being added with another 7.5 resistors, we have:
I = 9 volts / (5+5+7.5 ohms)
I = 0.529 ampere
The answer to the question is the letter "D. decrease; 0.51 amps".
