Question

Recitation Work - 5 In order to get full credit, you need to show all your work.

question 1.

A force Fx = cx^3 (c = 3.0 N/m^3) acts on an object with mass 40 kg that is sliding along a rough horizontal floor (x-axis) with coefficient of kinetic friction of 0.2. A) What is the work done by the force Fx on this object as it slides from x1 = 0.0 m to x2 = 6.0 m?

B) What is the work done by the force of friction on this object as it slides from x1 = 0.0 m to x2 = 6.0 m?

C) If the object has a kinetic energy of 1300 J at x2 = 6.0 m, what was its kinetic energy at x1 = 0.0 m?

question 2)

Recitation Work 6

In order to get full credit, you need to show all your work.

$//img.homeworklib.com/questions/956c13e0-20d9-11ec-87e0-f16441da7f60.jpg?x-oss-process=image/resize,w_560$ A roller coaster car of mass 300 kg. The car is released from rest at a height h above the ground and slides along the track shown. The car encounters a loop of radius 10.0 m, as shown. Assume that the initial height h is great enough so that the car never loses contact with the track. At the top of the loop the normal force on the car by the track is 400 N.

1. Draw the forces acting at the top of the loop, and apply Newton’s 2^nd law in the radial direction to find the speed of the car at the top of the loop?

2. Under the above conditions, what would be the maximum height of release, so that the amount of thermal energy produced by friction from the point of release to the top of the loop does not exceed 5000 J?

Answer 1

(A) с e che work done with or dare - Schede = { case 1 Wine 3x6 = 972] (B (c) Force = ung= 0.2x40x9.8=78.4N Work done we = f cx = 78.4x(6-0) = 470.47 Force F is trying to increase kinetic energy and friction f is decreasing it so KE, & Wx - Wf = KĘ KE = 1300-972 + 470.4 = 798. 43 At top of loop & is centripetal force v

798.4 J = of Lor Alp e is centripetal force e = F + mg = 400+300x9.8 = 3340 N also E=mreop z3340 300 g = 3340 to = 10.55 m/s friction force work Ws = 5000 ] Using energy conservation mgh - Wf = 1 m + ong 2R 300x98xh- 5000 = 2*300*10.55 + 300x9,8x2xlo h=27.38m

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