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:
Answer:
Explanation:
Given that,
The wavelength of light,
The speed of light,
We need to find the frequency of light. We know that,
Where
f is the frequency
So,
So, the frequency of light is .
Answer;
- June 21
At 45 degrees latitude, the angle of the noon sun is lowest and the length of daylight is shortest on June 21.
Explanation;
-On June 21 you will note that the Northern Hemisphere is pitched toward the Sun. This means that the Sun's vertical ray is striking the Earth at the Tropic of Cancer (23.5 degrees N).
-Days tend to get longer in the northern hemisphere from December 21 to June 21, and then grow shorter from June 21 to December 21. The June solstice is the summer solstice in the Northern Hemisphere and the winter solstice in the Southern Hemisphere. The date varies between June 20 and June 22, depending on the year, and the local time zone.
<u>Harmful</u><u />
-causes heat; if it's not used correctly, it can cause injury
-when falling, the friction between your knee/leg and the ground can cause scrapes
<u>
</u><u>Helpful</u><u />
-helps stop the bike, the brakes rub against the tire which slows it down to a stop
-it can also help move the bike; the chains rub against tires which accelerate the bike
Answer:
10miles/second
Explanation:
Change in velocity of the bird is expressed as the difference between the final velocity and initial velocity of the body.
Change in velocity = Final velocity - initial velocity
Since the bird takes off from the tree, the initial velocity of the bird = 0miles/sec
Final velocity = 10miles/secs
Change in velocity = 10-0
Change in velocity = 10miles/second