Answer:
7.9
Explanation:
When we put the metal piece in the liquid (which is in the graduated cylinder), how much it goes up is equal to the volume of the piece we inserted.
So now we know that the volume of that piece of unknown metal is 7mL (which is the same as 7).
Density is .
So the density of that piece of metal is
Which leaves us with a final density of 7.9
The charges have opposite sign and magnitude
Explanation:
The magnitude of the electrostatic force between two electric charges is given by Coulomb's law:
where:
is the Coulomb's constant
are the two charges
r is the separation between the two charges
In this problem, we have:
F = 3.60 N is the force between the two charges
r = 30 cm = 0.30 m is their separation
The two charges have same magnitude, so
So we can rewrite the equation as
And solving for q:
Moreover, the force between the charges is attractive: we know that charges of same sign repel each other while charges of opposite sign attract each other, therefore the charges in this problem have opposite sign, so
Learn more about electric force:
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