Homework H4.I - Fa22

Problem statement
Solution video


Discussion and hints:

Recall the following four-step plan outline in the lecture book and discussed in lecture:

Step 1: FBD
Draw a free body diagram of the system made up of P. Which, if any, forces do non-conservative work on this system? Can you justify this from the FBD?

Step 2: Kinetics (work/energy equation)
Write down the work energy equation for P. Recall that the potential energy in a spring is 0.5*k*Δ2, where Δ is the stretch/compression in the spring. Δ is NOT equal to the length of the spring. Recall that the spring is unstretched at position 2.

Step 3: Kinematics
What kinematics do you need here?

Step 4: Solve
Solve your work/energy equation for the speed of P at position 2.

Any questions??

2 thoughts on “Homework H4.I - Fa22”

  1. Since we consider potential energy of a spring a scalar and conservative force, we don't need to calculate the work it does on the way from position 1 to 2, right? Even though at the start the spring force has a y component opposing the gravitational force and is effectively reducing the weight?

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