$m_1 = 70\textrm{u}$ $m_2 = 72\textrm{u}$ $m_3 = 73\textrm{u}$ $m_4 = 74\textrm{u}$ Giancoli 6th Edition, Chapter 20, Problem 61(4:26) Chapter 20, Problem 61 is solved. Start My Free Week View sample solution