Suggestions:- FBD(s): Draw FBDs of spool and truck individually.
- Newton-Euler: Use Euler equation for spool (about the center of the spool) as well as summation of forces in x- and y-directions. Use Euler equation for truck about its center of mass G as well as summation of forces in x- and y-directions.
- Kinematics: Note that the location where the cable comes off the spool is the IC for the spool. Therefore, the x-component of acceleration of that point is zero. Use this to relate the acceleration of the center of the spool (equivalently, the acceleration of the truck) to the angular acceleration of the spool.
- Solve
Treat the cable wrapped around the spool as being a thin ring having a mass equal to the total mass of the cable and having a radius of 0.075 meters. Recall that the mass moment of inertia of a thin ring is m*r^2.
Any questions?
6 comments:
Sorry, I could be way off, and it's a small thing, but did you mean .75 meters, not .075? Cause if not, I don't know where that number came from.
Ooops, I mistyped. You are correct.
do we need to subtract the weight of the length of cable already attached to the wall?
it seems trivial, but we're not given a number for the distance, so may i correctly assume that it doesn't matter?
You need to include only the cable that is included in your FBD of the spool/cable. I would place the tension force at the end of the cable as it comes off the spool. Therefore, there is no need to include the cable between the spool and the wall.
i am having a hard time drawing the fbd of the truck. how is the spool affecting it and if it has a force associated with its acceleration?
Nick,
Include the supports for the roller on the FBD for the truck. Then you can draw reaction forces on the pin at the center of the spool, which would also be drawn on the center of the spool FBD.
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