11.1.8: Momentum

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It turns out that \(\sum\mathbf{F}_{\text{net}}=m\mathbf{a}\) is a special case of Newton's second law. Newton determined that a net force was something that caused a time rate of change of momentum, \(\Delta\mathbf{p}/\Delta t\) or \(d\mathbf{p}/dt\), where momentum is defined as \(\mathbf{p} = m\mathbf{v}\). The two descriptions are the same if the mass of the object in question does not change. Therefore, if there is no net force acting on an object or a system of objects, the momentum does not change. This statement is called conservation of momentum. Conservation of momentum, along with conservation of energy, is used in analyzing collisions between objects.