$(10$ points$)$ Two blocks are moving toward each other and collide elastically. Mass of the first block $m_1=2\mathrm{.}0kg.$ Velocity of the first block $v_1=3\mathrm{.}0\frac{m}{s}.$ Mass of the second block $m_2=3\mathrm{.}0kg.$ Speed of the second block $v_2=4\mathrm{.}0\frac{m}{s}.$ Find velocity of the second block right after the collision. $($Perfect elastic collision$).$

A$.1\mathrm{.}6\frac{m}{s}$

B$.-1\mathrm{.}2\frac{m}{s}$

C$.0\mathrm{.}0\frac{m}{s}$

D$.0\mathrm{.}8\frac{m}{s}$

$(10$ points$)$ Two blocks are moving toward each other and collide inelastically; they stick to each other. Mass of the first block $m_1=2\mathrm{.}0kg.$ Velocity of the first block $v_1=3\mathrm{.}0\frac{m}{s}.$ Mass of the second block $m_2=3\mathrm{.}0kg.$ Speed of the second block $v_2=4\mathrm{.}0\frac{m}{s}.$ Find velocity of the two blocks right after the collision.

A$.-2\mathrm{.}4\frac{m}{s}$

B$.-1\mathrm{.}2\frac{m}{s}$

C$.1\mathrm{.}0\frac{m}{s}$

D$.1\mathrm{.}8\frac{m}{s}$