Work & Energy Fundamentals
Work happens when a force causes an object to move in the direction of the force. The formula for work is work = force × displacement × cosθ. Remember, work only occurs when the force causes displacement, and the force must have at least some component in the direction of motion.
Energy comes in different forms. Kinetic energy is the energy of motion, calculated as KE = ½mv². This equals the work needed to accelerate an object from rest to its current speed. Potential energy is stored energy, with gravitational PE = mgh. Together, kinetic and potential energy make up mechanical energy.
Forces can be either conservative (like gravity, which tends to restore objects to their original position) or non-conservative (like friction, which involves thermodynamic processes). When only conservative forces act, mechanical energy is conserved, meaning ME₁ = ME₂.
⚡ Energy Insight: The work-energy theorem states that total work equals the change in kinetic energy. If total work is positive, an object speeds up; if negative, it slows down; if zero, its speed doesn't change.
