So far we’ve applied the Work-Energy Theorem to a flying object, namely, Santa’s sleigh, and a rolling object, namely, a car braking to avoid hitting a deer. Today we’ll apply the that coffee mug we’ve been following through this blog series. We’ll use the falling object, to find the force generated on the mug when it falls into a pan of kitty litter. This Theorem scenario is one I frequently encounter as an falling objectengineering expert, and it’s something I’ve got to consider when designing objects that must withstand impact forces if they are dropped.
Here’s the Work-Energy Theorem formula again,
v]_{1}^{2}where v over a distance, _{2}d. As we follow our falling mug from its shelf, its mass, d. The mug’s speed the instant before it hits the ground is vand its final velocity when it comes to a full stop inside the litter is _{1, }v, or zero._{2} Inserting these values into the
The right side of the equation represents the kinetic energy that the mug acquired while in freefall. This energy will be transformed into Gaspard Gustave de Coriolis’ definition of work, which produces a depression in the litter due to the force of the plummeting mug. Now a problem arises with using the equation if we’re unable to measure the mug’s initial velocity, Law of Conservation of Energy to work for us to do just that.
Copyright 2016 – Philip J. O’Keefe, PE Engineering Expert Witness Blog
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