Homework H5.L - Fa22

Problem statement
Solution video

DISCUSSION THREAD

Discussion and hints:

Note that the animation above is for a generic set of parameter values that may or may not be the ones assigned for the problem this semester.

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

Step 1: FBDs
Draw a single free body diagram for the system made up of bar OA and particle P, combined.

Step 2: Kinetics (impulse/momentum)

  • From you FBD above, what can you say about the moments acting about the fixed point O in your system? What consequence does this have on the angular momentum about point O for the system?
  • Use the coefficient of restitution, COR, equation relating the "n-components" of velocity for P and end A of the bar. (You may want to review Section 4.C of the lecture book in regard to impacts and the COR.)

Step 3: Kinematics
Note that bar OA rotates about point O. What does that say about the direction of the velocity of point A on the bar after impact? Study the animation above. Do your kinematics agree with what you see about the direction of the velocity of A?

Step 4: Solve
Solve your equations above for the speed of slider B.


Any questions?

7 thoughts on “Homework H5.L - Fa22”

  1. Do P and A have the same velocity in the n direction after the impact? If I plug that and the initial condition that the bar is stationary into the coefficient of restitution equation, I get 0 = -2v_2 / v_B1, making v_2 equal to 0, but I feel like that doesn't make sense.

    1. You know P and A have the same velocity from the COR equation, so if you plug that result back into the equation you will of course get 0.

      Once you know Vp2=Va2, move on to conservation of momentum equations

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