Question

a force of 15 N is applied to a 30-kg block that is at rest on a perfectly smooth, level surface

Answer 1

I assume, the task is to find block's acceleration. Since the surface is perfectly smooth, the only force acting on the block in horizontal direction is $F = 15N$. Then, according to the second Newton's law, the acceleration is:

$$a = \dfrac{F}{m}$$

where $m = 30kg$ is the mass of the block. Thus, obtain:

$$a = \dfrac{15N}{30kg} = 0.5m/s^2$$

Answer. 0.5 m/s^2.