Answer:
1280 mg
Explanation:
Radioactive decay is a phenomenon that occurs when a certain isotope of an element, said to be radioactive, decays, turning into a lighter nucleus and emitting radiation + energy in the process.
The radioactive decay of this isotope of polonium is described by the equation

where
is the amount of polonium left after time t
is the amount of polonium t time t = 0
is the half-life of the polonium, in days (it is the time it takes for the initial element to halve its amount)
IN this problem, we know that:
After t = 560 days, the amount of polonium left is
. Therefore, we can re-arrange the equation, substituting t = 560 d, and solve for
to find the initial amount of polonium:

Don’t forget about the formulas!
P=E/T
E=P•T
T=E/P
P= 45,000J / 90sec
500W is your answer
<u>Statement</u><u>:</u>
A force is required to accelerate a 600 g ball from rest to 14 m/s in 0.1 s.
<u>To </u><u>find </u><u>out</u><u>:</u>
The force required to accelerate the ball.
<u>Solution</u><u>:</u>
- Mass of the ball (m) = 600 g = 0.6 Kg
- Initial velocity (u) = 0 m/s [it was at rest]
- Final velocity (v) = 14 m/s
- Time (t) = 0.1 s
- Let the acceleration be a.
- We know the equation of motion,
- v = u + at
- Therefore, putting the values in the above formula, we get
- 14 m/s = 0 m/s + a × 0.1 s
- or, 14 m/s ÷ 0.1 s = a
- or, a = 140 m/s²
- Let the force be F.
- We know, the formula : F = ma
- Putting the values in the above formula, we get
- F = 0.6 Kg × 140 m/s²
- or, F = 84 N
<u>Answer</u><u>:</u>
The force required to accelerate the ball is 84 N and this force acts along the direction of motion.
Hope you could understand.
If you have any query, feel free to ask.