Torquin' Through Monday

Honors Physics completed their discussion of simple machines. We reviewed the types of simple machines, described how they functioned to make work easier and the two formulas for mechanical advantage. Added in the concept of efficiency emphasized the connection between the action of many of the simple machines and the concepts we've been covering in the rotational motion unit. Tomorrow, a lab that takes us back to centripetal force and tangential velocity. Wednesday, review and Thursday will be exam day.

Physics B conducted a lab investigation on rotational equilibrium. Setting up balanced torques for a variety of masses demonstrated clearly that force (weight) was not the only player in the game. Lever arm is critically important and rotational equilibrium is dependent not on balanced forces but on balanced torques. Tomorrow, we'll discuss the lab in more detail before continuing on with our discussion of rotational inertia and angular momentum.

Physics F spent time with rotational inertia and applied that idea to rolling. How easily an object rotates or rolls depends on its moment of inertia, and that depends on the object's mass and the distribution of that mass around the rotational axis. For single objects, there are often several axes around rotation can occur, but it is easier for some than for others. We looked at some moment of inertia formulas for simple shapes and it became clear why for a hoop and a ball, with identical masses and radii, the ball would always win a race when propelled by the same force - smaller moment of inertia = easier rotation.

Physical Science took time to discuss laboratory write ups. There's been problems in that area, so with the lab we just completed as a guinea pig, we looked at what each section of the lab write up should contain and what needed to be done to the current labs to bring them up to code. Work on your rewrites tonight and let's see how things look tomorrow.

Homework

Honors Physics: 8.4 Section Review and p. 308 #39 - 43
Physics B: None
Physics F: p.165, 166 in packet #7-13 and 27-30
Physical Science: Rewrite lab write ups for simple machines labs