What is Work? • Work is the process of moving an object by applying a force • The object must move for work to be done • The force must cause the movement • Work is a scalar quantity • Units are Joules Work in One Dimension • Only the force in the direction of the displacement contributes to the work done Non-Constant Forces • Work done is the area under the force vs. displacement graph Hooke’s Law • The more you stretch or compress a string, the greater the force of the spring • The spring’s force is opposite the direction of its displacement from equilibrium • Model this as a linear relationship, where the force applied by the spring is equal to a constant (the spring constant) multiplied by the spring’s displacement from its equilibrium (rest) position • F_s=−kx • Slope of the graph gives you the spring constant, k (in N/m) Work Done in Compressing a Spring • A spring obeys Hooke’s Law. How much work is done in compressing the spring from equilibrium to some point x? Work Done in Compressing a Non-Linear Spring Work in Multiple Dimensions Work-Energy Theorem Example: Velocity from an F-d Graph • Determine the object’s final speed.
