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PE of a. A New Kind of Potential: Elastic PE. Consider a toy gun…. Ohh … A DART gun!. What makes the dart shoot out? Where does the Kinetic Energy come from??. PE of a Spring. The Potential Energy ( PE elastic ) of a spring is described by:. PE of a Spring.
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PE of a A New Kind of Potential: Elastic PE
Consider a toy gun… Ohh… A DART gun! • What makes the dart shoot out? Where does the Kinetic Energy come from??
PE of a Spring • The Potential Energy (PEelastic) of a spring is described by:
PE of a Spring • k is the spring constant. Its different for every spring. (N/m) • x is the displacement of the spring. How much its stretched or squished… (m)
Spring Properties • As you pull a spring, it gets harder to pull the farther you go. • This is equally true if you try to compress it from it’s resting state. • The amount of Forceneeded to stretch OR compress a spring is shown by Hooke’s Law:
An Example: • A spring hanging vertically measures 0.3m. When a 1kg weight is attached, the spring stretches to a length of 0.8m. Determine the spring constant.
Another Example: • A spring of spring constant k= 50 N/m is compressed 50cm. How fast will it shoot a 0.010kg dart when released?
Putting it all together • James Bond (80kg) is driving at 80m/s in his Prius when he goes off a 100m cliff. His spring ejection mechanism has a spring constant of k=500 N/m and has been compressed 2m to fit in the car. Unfortunately his parachute fails… How fast is Mr. Bond going to hit the ground?