00318    a2200109   4500020001500000082001300015100002400028245007100052260005700123300001600180650001200196  a074925131X  a530bOPE  aThe open university  aScience b a second level coursebdiscovering physics b unit 6,'7  aKeynesbThe Open University of Sri Lankac1994g1994  a97p.c30cm.  aPhysics