Explanation :
In thermodynamics, a system is region or part of space which is being studied and observed while the surrounding is the region or space around the system which interacts with the system.
Here in the experiment ,system which is observed is reaction or changes when citric acid and sodium bicarbonate are mixed together. And the mixing is carried out in the calorimeter which serves as a surrounding around the system.
The reason behind the using the calorimeter is measure the energy change occurring during the reaction.
If a person weighs 63.4 KG they will weigh 139.773 but if you estimate it which in most cases you do it would be 139.8 :)
Answer:
13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.
Explanation:
Length of the base = l
Width of the base = w
Height of the pyramid = h
Volume of the pyramid = 
We have:
Rate at which water is filled in cube = 
Square based pyramid:
l = 6 cm, w = 6 cm, h = 13 cm
Volume of the square based pyramid = V
Differentiating V with respect to dt:
Putting, h = 4 cm
13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.
Natural: Land mounds, Rivers
Human made: Country borders, cities
