Answer:
C) Use two batteries instead of one.
Explanation:
-Strength of an electromagnet depends on the electrical current which flows through the wires.
-Two batteries have a higher current than one and thus higher strength in the electromagnet.
The potential difference,electric current ,resistance and new electric current will be 12 V,4 A,3 Ω,2 A.
<h3>What is resistance?</h3>
Resistance is a type of opposition force due to which the flow of current is reduced in the material or wire. Resistance is the enemy of the flow of current.
The energy in terms of the charge and potential difference is;
E= qV
60=5 C × V
V= 12 V
The electric current is found as;

From the ohm's law;
V=IR
12=4 ×R
R=3Ω
If the voltage is constant and the resistance is doubled, then the new electric current is half of the previous condition;

Hence, the potential difference,electric current ,resistance and new electric current will be 12 V,4 A,3 Ω,2 A.
To learn more about the resistance, refer to the link;
brainly.com/question/20708652
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Answer:
A. Positive, positive
Explanation:
As we defined the ground is the origin, as long as the rock is above the ground, its position would always be positive.
As for velocity, as long as the rock is moving upwards, its direction is also upward, so its velocity is always positive. The velocity will become negative when the rock falls down.