Physics Help Forum Work and Energy - spring

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Mar 9th 2018, 10:28 AM #1 Junior Member   Join Date: Mar 2018 Posts: 3 Work and Energy - spring Referring to Figure 2, the collar A (mass = 20 kg),is released from rest and slides down the rough rod (μ = 0.4), impacting the spring (k = 1.6 kN/m) after travelling a distance L of 0.5m. The rod is inclined at an angle θ = 60˚. Calculate, (i), the velocity of the collar at the moment of impact with the spring, and, (ii), the maximum compression of the spring. https://imgur.com/TorENhp - Link to figure 2 I did the first part and got the right velocity - 2.56 m/s but I am having troubles with the second part. I know that at the beginning there is only Epe (potential energy). Considering gravity acts vertically down then Epe = mgLsin60 , right? And that energy is going to be equal to the energy in the second compressed state = -mgxsin60 + 1/2 k(-x)^2 Are my assumptions correct? I am a bit confused whether the heights should be L and x respectively or Lsin60 and xsin60. What about Es? Would it be equal to 1/2 kx^2 or 1/2 k(xsin60)^2? Cheers
 Mar 9th 2018, 11:12 AM #2 Senior Member   Join Date: Jul 2009 Location: Kathu Posts: 132 Work and Energy - spring You should also add the work done by friction. This will be Mg*(Mu)*Cos(60)*(0.4)*(X)
 Mar 9th 2018, 12:02 PM #3 Senior Member   Join Date: Jun 2010 Location: NC Posts: 417 Hello Veirian... In problems with springs, I always liked to include the spring in the system. I might be late in replying (to help) but here are a couple of similar examples of possible interest. 1) This is a cohort of your problem. Box Bounces Between Springs | THERMO Spoken Here! 2) Here I model the linear spring internal energy as U = U[T, (Lo - L)]. Rock Falls onto a Spring | THERMO Spoken Here! Good luck with your studies... TSH studiot likes this.

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