Jan. 22
Objectives:
• formalize required notation: τ(tau) =torque, w=work, f=force (N, lb., kg, etc.) , d=distance (m, cm, ft., etc.)
• determine ideal mechanical advantage (IMA) of lever systems
Bell Ringer:
Seesaw’s are found on the playground and always have the fulcrum in the middle of the seesaw. In these questions all of the people are identical mass. Draw a seesaw with the appropriate number of people in the appropriate locations to answer the questions below. In these questions all of the people are identical mass.
1) Draw a seesaw showing two people which balance each other.
2) Find and draw two unique arrangements in which a seesaw showing three people which balance each other; no one can be on the fulcrum.
3) Find and draw two unique arrangements in which a seesaw carrying 4 people is balanced; no one can be on the fulcrum.
Lesson:
1) Return quiz; discuss questions students did wrong and how to correct them (re-do quiz as homework?)
2) See <http://science.howstuffworks.com/pulley1.htm> fro a description of force/distance tadeoffs.
3) Teach IMA = big force/small force or big distance/small distance, etc.
4) Complete "Mechanical Advantage" worksheet.
Assignment:
1) Draw your trebuchet plan; due next class:
(a) draw on A4 graph paper or A4 blank, printer paper