A radioactive source has a half life of 80s.
1 answer:
Let's assume that the initial quantity of nuclides is 100.
If 7/8 of 100 has decayed, we conclude that 87.5 has decayed.
This means that 1/8 remains from the original amount of 100, which results in 12.5 remaining.
To find out how many Half-lives it took for the sample to drop from 100 to 12.5, we can establish that 3 Half-Lives have elapsed.
Given that each Half-Life is 80 seconds, the total time taken would be 240 seconds.
Therefore, the conclusion is that it will take 240 seconds.
If 7/8 of 100 has decayed, we conclude that 87.5 has decayed.
This means that 1/8 remains from the original amount of 100, which results in 12.5 remaining.
To find out how many Half-lives it took for the sample to drop from 100 to 12.5, we can establish that 3 Half-Lives have elapsed.
Given that each Half-Life is 80 seconds, the total time taken would be 240 seconds.
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Answer:
The initially bent young tree has been straightened by adjusting the tensions of the three guy wires to AB = 7 lb, AC = 8 lb, and AD = 10 lb. Please calculate the force and moment reactions at the trunk's base point O, disregarding the weight of the tree.
C and D are situated 3.1' from the y-axis, while B and C are located 5.4' from the x-axis, and A has a height of 5.2'.
Explanation:
Refer to the attached image.
Part 1) Which metal will cool the fastest?
To determine this, we need to consider the heat flow rate formula, which indicates the speed at which a substance can gain or lose heat:
where:
denotes the heat exchanged
indicates the duration
k represents the thermal conductivity of the material
A is the area over which heat transfer takes place
shows the change in temperature
x is the thickness of the substance
It is evident that the heat flow rate
is directly related to k, the thermal conductivity. Thus, a higher value of k means that the metal will cool more quickly.
Upon examining the thermal conductivity values for each metal, we observe:
- Aluminium: 237 W/(mK)
- Copper: 401 W/(mK)
- Gold: 314 W/(mK)
- Platinum: 69 W/(mK)
Consequently, copper has the highest heat flow rate, making it the metal that cools the fastest.
Part 2) Which sample of copper demonstrates the greatest increase in temperature
To address this part, we can examine how the heat exchanged Q correlates with temperature increase:
where m indicates the mass and Cs represents the specific heat capacity of the material. By rearranging the equation, we derive
As a result, it becomes clear that the temperature increase is inversely related to the mass m. Thus, the block exhibiting the highest temperature rise will be the one with the least mass, hence the right choice is A) 0.5 kg.
To determine this, we need to consider the heat flow rate formula, which indicates the speed at which a substance can gain or lose heat:
where:
k represents the thermal conductivity of the material
A is the area over which heat transfer takes place
x is the thickness of the substance
It is evident that the heat flow rate
Upon examining the thermal conductivity values for each metal, we observe:
- Aluminium: 237 W/(mK)
- Copper: 401 W/(mK)
- Gold: 314 W/(mK)
- Platinum: 69 W/(mK)
Consequently, copper has the highest heat flow rate, making it the metal that cools the fastest.
Part 2) Which sample of copper demonstrates the greatest increase in temperature
To address this part, we can examine how the heat exchanged Q correlates with temperature increase
where m indicates the mass and Cs represents the specific heat capacity of the material. By rearranging the equation, we derive
As a result, it becomes clear that the temperature increase is inversely related to the mass m. Thus, the block exhibiting the highest temperature rise will be the one with the least mass, hence the right choice is A) 0.5 kg.