if he compresses the spring by 0.4 m and release it, what is the acceleration of the launcher as the spring reaches its natural length

Question

anonymous · Answer

Well, as we know from Hooke's law
$$F=-kx$$
But as we know from Newton's law 
$$F=ma$$
So $$-kx=ma$$
and $$a=(-k*x)\div(m)$$
It seems as though there is more to this problem than what you typed, because the mass of the object and the spring constant are not given, so no numerical value can be given.

anonymous · Answer

dwight uses a spring (k=70n/m) on a horizontal surface to make a launcher for model cars. the spring is attached to a holder that has a mass of 0.3 kg. if he compresses the spring and releases it, the launcher will move back and forth in periodic motion

Thats the whole question that's all it gives me