Question

help with part 5

1. A 125-kg load is lifted 12.0 m vertically with an acceleration a -0.32g by a single cable. Determine: (a) the tension in the cable, (b) the net work done on the load, (c) the work done by the cable on the load, (d) the work done by gravity on the load, and (e) the final speed of the load assuming it started from rest. 2. A 1.60-m tall person lifts a 2.10-kg book from the ground so it is 2.20 m above the ground. What is the potential energy of the book relative to (a) the ground (b) and the top of the person's head? (c) How is the work done by the person related to the answers in parts (a) and (b)? A 1200-kg car rolling on a horizontal surface has speed when it strikes a horizontal coiled spring and is brought to rest in a distance of 2.2 m. What is the spring stiffness constant of the spring? 4. A 58 kg skier is coasting down a 250 slope as shown. Near the top of the slope, her speed is 3.6 m/s. She accelerates down the slope because of the gravitational force, even though a kinetic frictional force of magnitude 71 N opposes her motion. Ignoring air resistance, determine the speed at a point that is displaced 57 m downhill. 5. The gymnast leaves the trampoline at an initial height of 1.20 m and reaches a maximum height of 4.80 m before falling back down. What was the initial speed of the gymnast? 6. A 10.0kg block is released from point A in figure. The track is friction- less except for the portion BC, of length 6.00m. The block travels down the track, hits a spring of force constant k-2250N/m, and compresses it 0.300m from its equilibrium position before coming to rest momentarily. Determine the coefficient of kinetic friction between surface BC and block.

Answer 1

5.

using 3rd equation of motion

v^2 = 2 g (h2-h1)

v^2 = 2* 9.8* ( 4.8 - 1.2)

v = 8.4 m/s

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