43. Two blocks, each of mass_m. = 3.50 kg, are hung from the ceiling of an elevator as in Figure P5.43. (a) If the elevator moves with an upward acceleration a of magni- tude 1.60 m/s², find the tensions T₁ and T₂ in the upper and lower strings. (b) If the strings can withstand a maximum tension of 85.0 N, what maximum accelera- tion can the elevator have before a string breaks? m T₁ m T₂