The leg and cast in Figure P4.18 weigh 300 N, with the center of mass as indicat

Question

The leg and cast in Figure P4.18 weigh 300 N, with the center of mass as indicated by the blue arrow in the diagram. The counterbalance w1 weighs 100 N. Determine the weight w2 and the angle ? needed so that no force is exerted on the hip joint by the leg plus cast. Two people are pulling a boat through the water as in Figure P4.20. Each exerts a force of 600 N directed at a ? = 25.0degree angle relative to the forward motion of the boat. If the boat moves with constant velocity, find the resistive force Frightarrow exerted by the water on the boat.

Explanation / Answer

T1 = w1 = 100 N and T2 = w2
so , T1cos40 = T2cosa
T2 =100cos40 /cosa = 76.60/cosa

in vertical :
T1sin40 + T2sina = 300
100sin40 + (76.60/cosa)sina = 300
76.60tana = 235.72
a = tan-1(235.72/76.60) =72 degrees

w2 = T2 = 76.60/cos72 = 247.85 N


b) Fnet = 600cos25 i + 600sin25j + 600cos25 - 600sin25    = 2 x 600cos45
so F   = 1200cos45 = 848.53 N

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.