Physical changes are those which do not affect the chemical properties of a substance. For example, when a paper is cut, the two pieces obtained are still paper. The chemical properties have not changed. Only, physically when one piece is cut to two. A chemical change occurs when the chemical properties change and a new substance with different chemical properties is obtained. For example, when the paper is burnt, it turns to ashes. Hence, this is a chemical change.
When a substance undergoes a physical change, the physical properties of the substance changes like the state (solid to liquid during melting), shape, size, volume etc. Many physical changes are reversible whereas, in general many chemical changes are irreversible.
<span>Which of the following forms of electromagnetic waves is LEAST dangerous to the human body? B
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Answer:
Power = 30 [watts]
Explanation:
Initia data:
F = force = 30[N]
d = displacement = 2 [m]
By definition we know that work is equal to the product of force by the distance displaced
Therefore:
W = F * d = 30 * 2
W = 60 [J]
And power is defined as the amount of work done in a given time interval
time = t = 2 [sec]
Power = W / t
Power = 60 / 2
Power = 30 [W]
C :<em>2 atoms of Oxygen can probably join 1 Silicon Atom</em>
