The correct answer is I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.
Elements are pure substances but these elements also make other things such as water. The water molecule is made of two elements called oxygen and Hydrogen. Now water itself is a pure substance as it is chemically bonded hydrogen and Oxygen but it is composed of more than one element
I believe that some are and some aren’t… sorry I’m not to well on this.
Answer:
Average speed, As = 2.2 [m/s]
Explanation:
To solve these types of problems we must remember that the average of the speeds is determined by dividing the distance over time.
With the first speed and the time of 6 [s] we can calculate the distance.
V = x/t
where:
x = distance [m]
V = velocity = 1.1 [m/s]
t = time = 6 [s]
x1 = V*t
X1 = 1.1*6
X1 = 6.6 [m]
Now with the second velocity and 6 [s], we can calculate the second distance.
X2 = 3.3*6
X2 = 19.8 [m]
Now we have to calculate the average speed. The total distance is x = x1 +x2
X = 19.8 + 6.6 = 26.4 [m]
and the total time is 12 [s]
Therefore:
As = 26.4/12
As = 2.2 [m/s]
Remember that the total
velocity of the motion is the vector sum of the velocity you would have in
still water and the stream. Always place the vectors carefully to be able to
come up with an accurate sum vector.
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