A 40 kg test object moving at 2 m/s is brought to rest without rebound. The current design stops it in 0.08 s; a thicker training mat stops it in 0.2 s. Consider only the contact force along the horizontal direction and use average force = momentum change / stopping time. The proposed design spreads deceleration over a longer time, but is heavier to move and can obstruct a doorway. Evaluate adoption for students and staff who move the equipment, using both a force calculation and wider implications. Evidence limitation: A test mass cannot establish medical safety; trained review and realistic impact tests are required.

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Momentum-change magnitude 80 kg m/s; average force falls from 1000 N to 400 N. A conditional, tested adoption is defensible; average force alone does not establish complete safety or best value. The same test mass loses the same speed in both designs, so the impulse magnitude is 40 × 2 = 80 kg m/s. The longer stopping time changes the force, not the total required momentum change. The original average force is 80/0.08 = 1000 N and the proposed force is 80/0.2 = 400 N. Both act opposite the initial motion. Relate the calculation to the specific benefit: a thicker training mat spreads deceleration over a longer time. The smaller average contact force is evidence for improved performance under this test, not a claim that energy or momentum disappears. Balance that benefit against a practical consequence: the design is heavier to move and can obstruct a doorway. Include the needs of students and staff who move the equipment, rather than allowing the cheapest purchase price or lowest force alone to decide. A justified recommendation is a monitored trial with a stated acceptance test before broad adoption. A test mass cannot establish medical safety; trained review and realistic impact tests are required. Report peak force, durability and relevant access constraints alongside the average-force calculation.

Replacing an old training mat

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