Work needed = 23,520 J
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Further explanation
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Given
height = 12 m
mass = 200 kg
Required
work needed by the crane
Solution
Work is the transfer of energy caused by the force acting on a moving object
Work is the product of force with the displacement of objects.
Can be formulated
W = F x d
W = Work, J, Nm
F = Force, N
d = distance, m
F = m x g
Input the value :
W = mgd
W = 200 kg x 9.8 m/s²x12 m
W = 23520 J
Double Displacement Reaction
An element from each of two compounds switch places.
Example: compound + compound ⇒ compound + compound
Chemical reactions are processes in which substances change into other substances. A chemical reaction takes place if one or more of these occur:
Color changes - Different combinations of molecules reflect light differently. A color change indicates a change in molecules.
Heat content changes- In all chemical reactions, the heat content of the reactants and the heat content of the products is never the same. Sometimes the difference is great and can be easily detected. At other times, the difference is slight and more difficult to detect.
Gas produced - Whenever a gaseous product forms in a liquid solution, bubbles can be seen. A colorless gas produced in a reaction of solids is much harder to detect.
Precipitate forms- Precipitates are insoluble products formed by a reaction taking place in a liquid solution. This insoluble product will eventually settle to the bottom, but might immediately appear by turning the clear solution cloudy.
Different layers represent clouds made of gases that condense at different temperatures.
Regions in the milky way where density waves have caused gas clouds to crash into each other are called clumps.Clumps are molecular clouds (interstellar clouds) with higher density,where lots of dust and gs cores resides. These clouds are the beginning of stars.
Answer:
Explanation:
Given
Volume of paint is 
Area of cover 
Suppose paint to be a rectangular box with thickness t and volume V
therefore we can write as
