Demonstrate the difference between weight and inertia in two distinct cases.

Pulling slowly on the bottom string will break the top string first as it has the added force due to the weight of the wooden block. This means the top string will surpass the maximum tension these strings can support before the bottom string.

Pulling quickly and forcefully on the bottom string should break it if the force was larger than the maximum tension the string can support. But it should impart only a small impulse on the block as Δt « 1. Since the force doesn't act on the block long enough to accelerate it, it delivers a negligible force to the top string. Updated on 05/30/13