Answer:at 21.6 min they were separated by 12 km
Explanation:
We can consider the next diagram
B2------15km/h------->Dock
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B1 at 20km/h
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V
So by the time B1 leaves, being B2 traveling at constant 15km/h and getting to the dock one hour later means it was at 15km from the dock, the other boat, B1 is at a distance at a given time, considering constant speed of 20km/h*t going south, where t is in hours, meanwhile from the dock the B2 is at a distance of (15km-15km/h*t), t=0, when it is 8pm.
Then we have a right triangle and the distance from boat B1 to boat B2, can be measured as the square root of (15-15*t)^2 +(20*t)^2. We are looking for a minimum, then we have to find the derivative with respect to t. This is 5*(25*t-9)/(sqrt(25*t^2-18*t+9)), this derivative is zero at t=9/25=0,36 h = 21.6 min, now to be sure it is a minimum we apply the second derivative criteria that states that if the second derivative at the given critical point is positive it means here we have a minimum, and by calculating the second derivative we find it is 720/(25 t^2 - 18 t + 9)^(3/2) that is positive at t=9/25, then we have our answer. And besides replacing the value of t we get the distance is 12 km.
Answer:
- Water gained: 10
- Iron lost: -10
Explanation:
Given: Hot iron bar is placed 100ml 22C water, the water temperature rises to 32C
To find: How much heat the water gain, how much heat did the iron bar lost
Formula:Q = change T x C x M
Solve:
<u>How much heat water gained</u>
Initial heat = 22, then rose to 32. To find how much heat the water gained, simply subtract the current heat by the initial heat.
32 - 22 = 10
The water gained 10 amounts of heat.
<u>How much heat Iron lost</u>
Current heat = 32, then dropped to 22. To find how much heat the Iron lost, simply subtract the initial heat by the current heat.
22 - 32 = -10
The Iron lost -10 amounts of water.
Answer:
In biological taxonomy, a domain (also superregnum, superkingdom, or empire) is a taxon in the highest rank of organisms, higher than a kingdom. ... The three-domain system of Carl Woese, introduced in 1990, with top-level groupings of Archaea, Bacteria, and Eukaryota domains.
Answer:
true
Explanation:
as long as it is the right conductive material
