Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information.... 
Home Conservation Laws Work: The Transfer of Mechanical Energy Examples A toy gun  
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A toy gunA toy gun uses a spring with a spring constant of 10 N/m to shoot a pingpong ball of mass 5 g. The spring is compressed to 10 cm shorter than its equilibrium length when the gun is loaded. At what speed is the ball released? The equilibrium point is the natural choice for a reference point. Using the equation found previously for the work, we have
The spring loses contact with the ball at the equilibrium point, so the final potential energy is PE_{f} = 0 . The initial potential energy is
The loss in potential energy of 0.05 J means an increase in kinetic energy of the same amount. The velocity of the ball is found by solving the equation KE = (1/2)mv^{2} for v,


Home Conservation Laws Work: The Transfer of Mechanical Energy Examples A toy gun 