The drawing shows two crates that are connected by a steel wire that passes over a pulley. The unstretched length of the wire is 1.70 m, and its cross-sectional area is 1.25 10-5 m2. The pulley is frictionless and massless. When the crates are accelerating, determine the change in length of the wire. Ignore the mass of the wire.

 The change in length of the wire is= 8.613*10⁻⁷ m

Explanation:

                        The formula for Young's Modulus = Stress/ Strain

                                                      where x represents the change in length.

Rearranging the equation and making F/A the subject of the formula gives us            

                                                         

The use of area is not required as we have assumed the the force of Atmosphere is being applied on the crates which means

                                                    F/A = Atmospheric Pressure

                                                    1 atm = 101325 Pa

now solve:

                                                     101325 = (2.10*10¹¹ Pa) * (x/1.7)

Therefore, x= 8.613*10⁻⁷ m

The answer is a i think

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