1. M.J. Matehkolaee, K. Majidian, Eur. J. Phy. Edu., 4,
2013#
2. R. Resnick, D. Halliday, and K. S. Krane, Physics
(Vol. 1), 4th Ed. New York: Wiley, 1992#
3. T.S. Aurora, Phy. Edu., 29, 1994#
4. B.A. Sherwood, W.H. Bernard, Amer.J. Phy., 52,
1984#
5. D.C.H. Poon, The Phy. Teacher, 44, 2006#
6. C. E. Mungan,
The Phy. Teacher, 45, 2007#
7. B. A. Sherwood, Amer.J. Phy., 51, 1983#