B they start moving around and stop staying in an orderly manner
Answer:
C) steel turning to rust in salt air
Explanation:
The missing options are:
A) ice melting to form liquid water
B) water boiling to form steam
C) steel turning to rust in salt air
D) sugar dissolving into hot coffee
In a chemical change the atoms of the reacting compounds are reordered forming new compounds. In a chemical change, new compounds appear, but in a physical change not.
Then, change of states like ice melting and water boiling are not chemical changes.
During steel rust, components of steel, like iron, are oxidized, that is, reacts with oxygen forming oxides.
The dissolution of sugar into hot coffee is a physical change in which sugar molecules get further apart in the coffee, but they don't change.
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Answer:
The weights are 1 kg, 3kg, 9kg and 27kg.
Explanation:
The weights are 1 kg, 3kg, 9kg and 27kg.
1+3+9+27= 40
27+9+3= 39
27+9+3-1=38
27+9+1=37
27+9=36
27+9-1=35
27+9+1-3=34
27+9-3=33
27+9-3-1=32
27+3+1=31
27+3=30
27+3-1=29
27+1=28
27
27-1=26
27+1-3=25
27-3=24
27-3-1=23
27+3+1-9=22
27+3-9=21
27+3-9-1=20
Like this all the weights from 1 to 40 kg can be made using 1,3,9 and 27 kg.
Answer:
b. The force exerted by the piston on the object is less than F because the piston is accelerating downward.
Explanation:
Given that object exerts a downward force F on the piston that accelerates the piston downward.
An object can accelerate if the net force acting on it is non-zero.
Here, the piston is acceleration in the downward direction, so the net for on the piston is in the downward direction.
Force due to object, F, is in the downward direction while the force exerted by the piston on the object is in the upward direction.
As the acceleration of the piston is in the downward direction, so the downward force is more.
Therefore, the force exerted by the piston on the object is less than F because the piston is accelerating downward.
Hence, option (b) is correct.