$$ \begin{cases} m_A&=460\ut{g}=0.460\ut{kg}\\m_B&=500\ut{g}=0.500\ut{kg}\\R&=8.00\ut{cm}=8.00\times10^{-2}\ut{m}\\\Delta y_{0\rarr5}&=75.0\ut{cm}=0.750\ut{m}\\g&=9.80665\ut{m/s^2}\end{cases} $$$$\ab{a}$$$$S=v_0t+\frac{1}{2}at^2,$$$$ \begin{aligned}a&=\frac{2\Delta y}{t^2}\\&=\frac{3}{50}\ut{m/s^2}\\&=6.00\times10^{-2}\ut{m/s^2}\\&=6.00\ut{cm/s^2}\\\end{aligned} $$$$\ab{b}$$$$ \begin{aligned}\Si..