$($II$)$ Two masses are connected by a string as shown in Fig. $34.$ Mass $m_A=4\mathrm{.}0kg$ rests on a frictionless incline plane, while $m_B=5\mathrm{.}0kg$ is initially held at a height of $h=0\mathrm{.}75m$ above the floor. $($a$)$ If $m_B$ is allowed to fall, what will be the resulting acceleration of the masses? $($b$)$ If the masses were initially at rest, use the kinematic equations to find their velocity just before $m_B$ hits the floor. $($c$)$ Use conservation of energy to find the velocity of the masses just before $m_B$ hits the floor. You should get the same answer as in part $($b$).$

FIGURE $34$

Problem $22.$