Question

If the child’s acceleration is 0.31m/s^2, what is the parent’s acceleration?

Answer 1

If $F1 = F2,$ then

$$m1*a1 = m2*a2,$$

where m - the mass, a - the acceleration.

$a2 = m1*a1/m2$

So, we must know child's and parent's masses to calculate parent's acceleration.