Momentum Test

A copper penny lay wedged upright between two stone pavers on the front stoop after I slipped through the ground-floor door. I braced my boots against the mortar line and pushed against the coin's ribbed edge with both hands. With a sudden click, the heavy metal disc broke loose from the grit, rolling forward across the concrete slab before toppling flat with a crisp chime. I paced over and stepped firmly onto its raised surface, claiming the prize right in the middle of the open terrace.