Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

1) Two blocks each of mass m = 2.98 kg are fastened to the top of an elevator as

ID: 1784396 • Letter: 1

Question

1) Two blocks each of mass m = 2.98 kg are fastened to the top of an elevator as in the figure. (a) If the elevator has an upward acceleration a = 1.60 m/s2, find the tensions Ti and T2 in the upper and lower strings. (b) If the strings can withstand a maximum tension of 91.0 N, what maximum acceleration can the elevator have before the upper string breaks? (show the steps of your calculation and indicate units to get credit) 2) A river has a steady speed of 0.600 m/s. A student swims upstream a distance of 1.00 km and swims back to the starting point. (a) If the student can swim at a speed of 1.40 m/s in still water, how long does the trip take? (b) How much time is required in still water for the same length swim? ur calculation and indicate units to get credit)

Explanation / Answer

a) T1 = 2m ( 9.81 + 1.6)

T1 = 2 × 2.98 × 11.41 = 68.0 N

) T2 = 2.98 × 11.41 = 34.0 N

b) if T = 91

91 = 2×2.98×(9.81 + a)

a = 5.46 m/s^2

2) upstream net speed is 0.800 m/s
downstream net is 2.00 m/s
t = d/v
up time + down time = total time
1000/0.800 + 1000/2.00 = 1250 + 500 = 1750

still water
2000/1.40 = 1428.57