In my opinion I believe it would be motion because depending on how fast the person is going it would determine the outcome of the race
Sorry this will probably be pretty long.
So think of the "control" as being something you yourself add to increase or decrease the effects in an experiment.
I'll give you an example so it is not as confusing.
Say you have decided to make an experiment on plants. Which plant can grow the fastest on which type of liquid? What is being added to this experiment? The liquid! Or all of the liquids you used. Like if you used Coke, Lime Gatorade, Orange Gatorade, and Water. Each drink will EFFECT each plant differently.
Hope I was of any hope?
I believe the most appropriate answer would be to change the core from wood to iron. This is because iron is a magnetic material while wood is not magnetic hence cant acquire magnetism. Other factors that would increase the strength of electromagnet would be; increasing the amount of electric current, and increasing the number of windings.
Answer :]
to convert from g NaOH to mol NaOH. = 1.48 g NaOH are needed to neutralize the acid.
Answer: 28.4 g of aluminum oxide is produced by the reaction of 15.0 g of aluminum metal
Explanation:
To calculate the moles :
The balanced chemical equuation is:
According to stoichiometry :
4 moles of 
produce == 2 moles of 
Thus 0.556 moles of will produce=
of
Mass of 
Thus 28.4 g of aluminum oxide is produced by the reaction of 15.0 g of aluminum metal.
