Which of the following is NOT an indication that a chemical reaction took place?
1 answer:
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Answer:
C. 2.5 days/mi
Explanation:
Speed is defined as the distance covered by an object divided by the time taken to cover that distance:
where
S is the distance covered
t is the time taken
At the numerator of the fraction, we have distance, which is a lenght. Lenght is measured in different possible units: meters (m), kilometer (km), mile (mi), centimeter (cm)...
At the denominator, we have a time, which can be measured in seconds (s), minutes (min), hours (h), days..
According to this, we can see that option
C. 2.5 days/mi
cannot represent a speed. In fact, at the numeratore we have days (which is a measure of time), while at the denominator we have mile (which is a measure of length), so in this fraction distance and time are inverted, therefore this cannot be a measurement of a speed.
Answer:
Answer is explained in the explanation section below.
Explanation:
Solution:
We know from the Coulomb's Law that, Coulomb's force is directly proportional to the product of two charges q1 and q2 and inversely proportional to the square of the radius between them.
So,
F =
Now, we are asked to get the greatest force. So, in order to do that, product of the charges must be greatest because the force and product of charges are directly proportional.
Let's suppose, q1 = q
So,
if q1 = q
then
q2 = Q-q
Product of Charges = q1 x q2
Now, it is:
Product of Charges = q x (Q-q)
So,
Product of Charges = qQ -
And the expression qQ - is clearly a quadratic expression. And clearly its roots are 0 and Q.
So, the highest value of the quadratic equation will be surely at mid-point between the two roots 0 and Q.
So, the midpoint is:
q =
q = Q/2 and it is the highest value of each charge in order to get the greatest force.