Conservation laws

• What Is the Relation Between Potential Energy and Force?
  For a conservative force, force is the negative slope or gradient of potential energy; see how to calculate it and interpret the sign.
• Kinetic Energy vs Momentum: What Is the Difference?
  Kinetic energy and momentum both describe motion, but they differ in direction, units, mass dependence, and conservation laws.
• Is Rotational Kinetic Energy Conserved?
  Rotational kinetic energy is not always conserved. Learn how torque, work, and energy transfers determine whether it stays constant.
• Can Internal Forces Change a System’s Total Momentum?
  Internal forces can redistribute momentum among a system’s parts, but they cannot change its total momentum when the system is isolated.