Using reasoning, determine the number of marbles that you would expect to fit if you doubled the diameter (new diameter = 16 cm). Explain how you determined your answer.

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current

The upward force acting on the wing of a airplane in flight is known as the "lift" force. (d)

It would stay the same