A block of mass m $=0\mathrm{.}51$ kg attached to a spring with force constant $119$ N$/$m is free to move on a frictionless, horizontal surface . The block is released from rest after the spring is stretched a distance

A $=0\mathrm{.}13$ m$.($Indicate the direction with the sign of your answer. Assume that the positive direction is to the right.$)$ 

 

The left end of a horizontal spring is attached to a vertical wall, and the right end is attached to a block of mass m which can slide left and right on a horizontal surface. The spring is stretched from its equilibrium position by a distance A$.$

$($a$)$ At that instant, find the force on the block.

 $($b$)$ At that instant, find its acceleration.

 

 

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