7. (II) Atwood's machine was an apparatus that allowed a
direct verification of Newton's second law. It could also be
used to measure g. Two equal blocks of mass M hang on
either side of a pulley; see Fig. 5.56. A small square rider of
mass m is placed on one block. When the block is released,
it accelerates for a distance H till the rider is caught by a
a
ring that allows the block to pass. From then on the system
moves at a constant speed which is measured by timing the
fall through a distance D. Show that
(2M + m)D
2mH12
where 1 is the time moved at constant speed.
m2
M
Hotez
D
M
FIGURE 5.56 Problem 7
