9. NL5Q9
A rightward force of 14.0-N is exerted on a block to accelerate it across a friction-free surface. It accelerates at 3.45
m/s/s. If a second block of identical mass is dropped onto the first block, then what is the acceleration when the same
14.0-N force is applied to it. (Assume that there is no sliding between the first and second block.)