1. Determine the center of mass for different objects and systems of objects
2. Calculate the magnitude of the total torque acting on an object
3. Identify forces and torques acting on a stationary extended object, and be able to apply the equilibrium torque condition.
4. Determine the torque of a simple machine: the lever.
1. Here the idea of equilibrium is extended to include NO CHANGE in ROTATIONAL motion. rotational motion does not occur in mechanics until year 3, so this idea needs to be introduced here, but nothing overly mathematical should be done. Systems that increase spin rate up or slow down spinning are clearly cases where rotational equilibrium is not the case. Disks spininng at a constant rate are in equilibrium, etc. 2.Similarly for torques: using example of opening a large door, develop idea that amount of angular acceleration will be proportional to how much you push, and where you pust wrt axis of rotation of door. Then talk about different directions (open/close the door) and develop a simplified way to do torque problems: only consider ones where forces are perpendicular to motion arms, producing either CCW or CW rotation (call these + or -) 3.Mention that torques are vectors b/c they are made up of forces...but they will be handled in greater depth later... 4.Keep simple machine discussion to a minimum because work has not yet been defined. It will come later, so this is the beginning of a work spiral. Instead, focus on the torque applied to a lever, the simplest of simple machines. The discussion of a lever is important obviously because this LO is about torque. Mechanical advantage can be mentioned, as well as the fact that the lever is a simple machine, but I wouldn't discuss other machines here 5.As for center of masss, keep it simple as well. It will be covered in more detail at beginning of module on momentum and impulse. Stick to discrete masses in 1-D. A lab activity determining the center of mass of a 2-D object is recommend as well