A cube, whose mass is $0\mathrm{.}520kg,$ is attached to a spring with a force constant of $154\frac{N}{m}.$ The cube rests upon a frictionless, horizontal surface $($shown in the figure below$).$

The cube is pulled to the right a distance $A=0\mathrm{.}120m$ from its equilibrium position $($the vertical dashed line$)$ and held motionless. The cube is then released from rest.

$($a$)$ At the instant of release, what is the magnitude of the spring force $($in $N)$ acting upon the cube?

$N$

$($b$)$ At that very instant, what is the magnitude of the cube's acceleration $($in $\frac{m}{s^2})?$

$\frac{m}{s^2}$

$($c$)$ In what direction does the acceleration vector point at the instant of release?

Away from the equilibrium position $($i$.$e$.,$ to the right in the figure$).$

Toward the equilibrium position $($i$.$e$.,$ to the left in the figure$).$

The direction is not defined $($i$.$e$.,$ the acceleration is zero$).$