Intuition would tell us that if an implosion and explosion of equal force occurred at the same time, they would cancel each other out and not much would happen! However, most implosions and explosions result in the object of intent breaking or shattering, so these pieces might simply break and fall without being sucked into the implosion or ejected outward in an explosion. Consider, for example, a container with a small explosive inside. We apply a great pressure to the outside of the container until it can no longer stand the pressure. At the instant it collapses (implodes due to pressure), we detonate the explosive, one that just happens to have enough force to counteract the pressure. The resulting actions would effectively cancel out and leave the container as it were!

You might hear the term implosion used for the demolitions of buildings and structures. In this context, the implosion is actually a controlled explosion (or controlled demolition) because explosives are used in the process. Engineers carefully place explosives at key points within the building such that when they blow up, the building loses its internal support and can collapse on itself (due to gravity). From the outside, it would appear as if the building just crumbled in on itself. A well done demolition destroys the building but also leaves surrounding buildings and area undamaged from ejected or falling pieces. There are many great videos online of well-timed controlled demolitions, and of course plenty of examples of demolition blunders as well!