Why is -1/5g is nigative here Wa = Fa-d = mgd cos 180° = -mg.dM Then we conclude that:* the work done by F therefore can be negative, positive or zero if the motionoccurred horizontally.{ 90 }Chapter 7: Kinetic Energy and WorkampleV An elevator with mass of m =500 kg is descending (moving downward)with speed vi = 4.0 m/s when its supporting cable begins to slip, allowingit to fall down with constant acceleration of a = g/5 as shown in the figure.(a) During the falling through a distance d = 12 m, what is the work Wg doneon the elevator by the gravitational force F , ?(b) ) During the 12 m fall, what is the work Wr done on the elevator by theupward pull (T) of the elevator cable?(c) What is the net-work W done on the cab during the fall? The net-work isthe sum ( E )of the works done by the forces acting on the cab:(d) What is the cab's kinetic energy at the end of the 12 m fall?O Solution:-Elevatorcablea. The falling and gravitational force F are in the sameDoesdirection ( 00), so7 negativeCabworkWg = Fg.d = mgd cos 0°DoespositiveworkWg = (500 kg) (9.8) (12 m) = 58800 J × 59 kJb. EF = ma →Fr – Fg= maFT = ma + Fg%3D та + mg 3 т(а + g)Wt = Frd cos 0 =m(a + g)d cos 0Does7 negativeW, = m(-8+8)d1g +g)d cos 0 = mg)d cos 0Cab-workDoes(4Wr(500 kg) |× 9.8 m/2)(12 m) cos 180° = -47 kJpositiveworkc. W = Wg + Wr = 58800 J – 47040 J =d. W + K. E.j = K.E.f11760 J z 12 kJ121(500 kg) (4-mK.E.f = ¬mv;² + W =+ 11760 JK.E.f = 15760 J × 16 kJ91Chapter 7: Kinetic Energy and Workork done by a spring force1. The spring force is an example of variable force notconstant, its change with the displacement.Blockattachedto springx-0F,= 02. When the spring at equilibrium, that means x = 0,and it's at rest , there is no compressed nor extended.

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Answered: Why is -1/5g is nigative here

Science

Physics

Why is -1/5g is nigative here

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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