Homework H.4.J

HINTS

STEP 1 - FBD: Draw a SINGLE free body diagram (FBD) of the system including Block A, Block B and the cable. From this, determine which forces do work on this system.
STEP 2 - Kinetics:  Write down the work/energy equation. Determine the work done by the forces that you identified  above in STEP 1.
STEP 3 - Kinematics: Review the constrained motion kinematics from Section 1.D of the course lecture book. To this end, you will write down an expression for the length of the cable in terms of sA, sB and constants. Differentiate this expression to relate the speeds of A and B.
STEP 4 - Solve

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10 thoughts on “Homework H.4.J”

  1. Keep in mind that you need to use only the CHANGE in potential energy for the work energy equation. Typically, we define either the initial or final positions as DATUM lines for calculating the gravitational potentials. For this problem, you see that the change in potential energy for Block A is zero. For Block B, use the known change in position for A to calculate the positive change in potential for B.

    Does this help?

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