Question $8$

$1$ pts

At time $t=0,$ a rock of mass $m$ is moving along the $+y$ axis with initial speed $v_0,$ so the initial velocity vector is vec$(v{)}_i=v_0$hat$(j).$ A force of constant magnitude F is applied in the $-$x direction $)=(-$Fhat$(i)$ for a time $t.$ There is no gravity or other forces acting on the rock. Which of the following is the correct expression for the final speed of the rock, after the force has been applied.

$v_0+Ft$

$v_0+\frac{F}{m}t$

$\sqrt[\phantom{2}]{v_0^2+(\frac{Ft}{L}{)}^2}$

$v_0^2-(\frac{F}{m}{)}^{2}t$

None of the other answers is correct.