Pennies on a meter scale
You and a friend place pennies every 10 cm along a meter stick. You hold one end as a pivot and release the other end from a horizontal position. You note that the pennies near the pivot stay on the meter stick while the pennies near the released end are left behind.
a) At the instant that the (pivoted) meter stick is released (so while the stick is still horizontal) what is the acceleration of the released end of the meter stick (neglect the pennies)
b) How far should a penny be placed from the end of the meter stick so that it is not left behind.