¿Una bola de 5,44 kg se mueve con velocidad de 20 m/s y 6 s después se mueve a 11 m/s. ?Qué valor tiene la fuerza de fricción ejercida sobra la bola?

therefore, the efficiency is:

The relationship of both of them

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

//(b) both involve the use of levers;