Multiple Choice
Passage
Laparoscopy is a minimally invasive surgical procedure where small surgical instruments are inserted into the body through cannulas (hollow tubes 0.5 to 1.0 cm in diameter) . A cannula is inserted into the skin while sleeved around a trocar (Figure 1) . The skin incision can be made directly with a sharp-tipped trocar as it is being inserted with the cannula. If a blunt-tipped trocar is used, the incision is made beforehand with a surgical blade. After insertion, the trocar is removed, leaving the cannula as an access point for laparoscopic procedures.
Figure 1 Cannula, trocar, and two types of tipsLow-friction trocars increase surgical precision and reduce postoperative scarring. Friction between the skin and trocar tip is tested with synthetic skin and a stationary ramp whose surface is made of the same material as the trocar. For testing, the synthetic skin is pressed against the ramp's surface by a load, weighted to allow the skin to slide down at a constant speed (Figure 2) . In this setup, the weight of the synthetic skin layer is negligible.
Figure 2 Experimental setup to test the friction between trocar and skin
Adapted from W. Firme-Gustavo et al., (C) 2015 Society of Laparoendoscopic Surgeons.
-After the load leaves the ramp, it slides on a horizontal table with a coefficient of kinetic friction μk of 0.1 and a coefficient of static friction μs of 0.3. If the direction of the load's velocity is positive, what is the acceleration of the load? (Note: Use g = 10 m/s2.)
A) −3 m/s2
B) −1 m/s2
C) 1 m/s2
D) 3 m/s2
Correct Answer:

Verified
Correct Answer:
Verified
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