Answer:
3
Explanation:
The half-life is the time it takes for the amount of radioactive isotope to halve. Therefore, we have:
- After 1 half-life, only 1/2 of the element will be left
- After 2 half-lives, only 1/4 of the element will be left
- After 3 half-lives, only 1/8 of the element will be left
So, it will take 3 half-lives for the element to become 1/8 of its original amount.
Mathematically, this can be also verified by using the equation
where
N(t) is the amount of the element left at time t
N0 is the initial amount of the element
is the half-life
Substituting 
(3 half-lives), we find
Since energy is lost in the roller coaster due to friction, the hill should little lower than the starting height since some of the kinetic energy at the bottom of the first hill is lost due to friction so it will not have as much potential energy at the top of the next hill.
A roller coaster is a good way to demonstrate the principle of conservation of energy. Recall that energy is neither created nor destroyed but can be converted from one form to another.
In a roller coaster, all the heights are not the same because energy is lost along the line. Therefore, the students must bear in mind that the hill should be at least a little lower than the starting height because some of the kinetic energy at the bottom of the first hill will be converted to other types of energy due to friction so it will not have as much potential energy at the top of the next hill.
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C. middle layer, density increases with depth as pressure increases
Explanation:
The mantle is the middle layer of the earth. It's density increases with depth as pressure increases.
- Based on the compositional division of the earth, our blue planet is divided into crust, mantle and the core.
- The crust is the lightest and the outermost layer of the earth.
- The mantle is the middle layer. Its density lies between that of the core and crust.
- The mantle is the largest layer and density increases with depth here.
- The core is a metallic ball. It is the most dense part of the earth.
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Answer: Individuals with high self efficacy will participate readily and more frequently, will put more effort in and persist longer, enhancing performance in sport and exercise
Each hour 430 quintillion Joules of energy from the sun hits the Earth.
In a year it is very hard to determine because of the night and different light levels.
