Conduction and convection both require some material substance
to move heat from one place to another, and there's none of that
between the sun and Earth.
The only way for thermal energy to move from place to place with
nothing in between is by the process of radiation, and that's how
it gets here from the sun.
I'm assuming your question refers to the train travels 81 km in 2 hours, as in that's the total distance covered versus the speed for those 2 hours, whereas the 90 km in 2 hours the second time around is the total distance not speed I would assume.
Now... if it was going 81 km for the first 2 hours and 90 km for the second 2 hours then the average speed would be the mean of these numbers, with that being 85.5 km. Though, I doubt that's your question.
With that said, 81 km covered by 2 hours and 90 km covered by 2 more hours. To acquire the km an hour average, we'll have to divide the distance by how many hours it traveled:
81 / 2 = 40.5
90 / 2 = 45
Meaning the train was going 40.5 km an hour for the first 2 hours and 45 km an hour for the second 2 hours. Now, to find the mean:
40.5 + 45 = 85.5 / 2 = 42.75
In-case you were wondering, the mean is the sum of all the numbers in a set, divided by the total amount of numbers in that set, take for instance:
3, 5, 9, 2, 1, 5. -> There are 6 numbers in this set.
3 + 5 + 9 + 2 + 1 + 5 = 25 -> 25 is the sum of these numbers.
25 / 6 = 4.2 (estimated) -> 4.2 is roughly the mean or average between the original set.
Anyhow, with that aside the average speed between this I would believe would be 42.75 km an hour. I hope that helps, have a great rest of your day! ^ ^
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A) gneiss
Explanation:
The likely rock that would be found here is gneiss.
A rock type that forms under a great deal of temperature and pressure is a metamorphic rock.
Such rocks would have their minerals crystallized when subjected to these extreme conditions.
- Metamorphic rocks are changed rocks that are formed when minerals in rocks are subjected to extreme pressure and temperature before they start melting.
- These rock type can form from either sedimentary or igneous rocks. In fact a metamorphic rock can also change into another one.
- Examples of metamorphic rocks are gneiss, schist, hornfels, marble etc.
Halite, limestone and sandstone are examples of sedimentary rocks that forms by the accumulation of sediments or precipitation of ions form solutions.
learn more:
Metamorphic change brainly.com/question/869769
#learnwithBrainly
The stretch of the spring is
The constant of the spring is k=15 N/m, so we can find the force produced by the weight by using Hook's law:
Answer:
It increases.
Explanation:
If a force acts in the same direction as the object's motion, then the force speeds the object up. Either way, a force will change the velocity of an object. And if the velocity of the object is changed, then the momentum of the object is changed.
