When an object with mass $m=4kg$ is hung vertically on a certain light spring that obeys Hooke's law, the spring stretches $4\mathrm{.}5cm.$ The stored potential energy $($in $J)$ in this spring for this case is:

A$)0\mathrm{.}9$

B$)0\mathrm{.}3$

C$)0\mathrm{.}7$

D$)0\mathrm{.}5$

E$)1\mathrm{.}2$

A $50-kg$ box initially at rest is pushed to the right along a horizontal surface by a constant horizontal force of $200N.$ If the surfaces in contact have a coefficient of kinetic friction of $0\mathrm{.}2,$ then the speed $($in

Q$15$

$\frac{m}{s})$ of the box after it has moved $5m$ is:

A$)5\mathrm{.}3$

B$)3\mathrm{.}5$

C$)4\mathrm{.}5$

D$)2\mathrm{.}6$

E$)1\mathrm{.}8$

A block of mass $m=4\mathrm{.}5kg$ is given an initial velocity $v_i=2\frac{m}{s}$ to the right and collides with a spring of force constant is $=500\frac{N}{m}.$ If the surface is frictionless, the maximum compression $x($in $m)$ of the spring after the collision will be:

A$)0\mathrm{.}13$

B$)0\mathrm{.}26$

C$)0\mathrm{.}16$

D$)0\mathrm{.}19$

E$)0\mathrm{.}22$