Two blocks each of mass m= 3.50 kg are fastened to the top of an elevator as in Figure P4.21.

 (a) If the elevator has an upward acceleration a=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 acceleration can the elevator have before the upper string breaks?

 

T m T m Ted Figure P4.21