Question

When a horizontal force of 7N acts on a block on a resistance free surface, it produces an acceleration of 3.5m/s^2. suppose a second 4kg block is dropped onto the first. what is the magnitude of the acceleration of the combination if the same force continues to act? Assume the second block does not slide off the first block.

Answer 1

first, find the mass
F=ma or m=F/a

that is the original mass.
Now,
F=(m+4)a
solve for a.