How are kinetic energy and work related?
The Nature of Kinetic Energy • Define kinetic energy 2 ways • In words: the work needed to accelerate an object from rest to its current velocity. (The energy an object possesses due to its motion) • Mathematically: K ≡ 1/2 mv2 • Derive the equation for kinetic energy from the equation for work, Newton’s second law, and the kinematic equations assuming constant force and acceleration. • Explain the difference between positive and negative work. • Negative work: reduces kinetic energy. Done by a conservative force such as gravity converts kinetic energy into potential energy. Done by sliding friction converts kinetic energy into thermal energy (heat). • Positive work: increases kinetic energy • Use the definition of kinetic energy and work in problem solving. • Sliding Friction: negative work = heat • Gravity Force: positive work = kinetic energy Homefun: Read 7.5, Problems 25 p.
