Key Equations

Key Equations

8.1 Linear Momentum, Force, and Impulse

impulse F net Δt F net Δt
impulse–momentum theorem Δp= F net Δt Δp= F net Δt
linear momentum p=mv p=mv
Newton’s second law in terms of momentum F net = Δp Δt F net = Δp Δt

8.2 Conservation of Momentum

law of conservation of momentum ptot = constant, or ptot = p′tot
conservation of momentum for two objects p1 + p2 = constant, or p1 + p2 = p′1 + p′2
angular momentum L = I ω ω

8.3 Elastic and Inelastic Collisions

conservation of momentum in any collision, including elastic collisionselastic collision m 1 v 1 + m 2 v 2 = m 1 v ′ 1 + m 2 v ′ 2 , m 1 v 1 + m 2 v 2 = m 1 v ′ 1 + m 2 v ′ 2 ,
conservation of momentum in a perfectly inelastic collision m 1 v 1 + m 2 v 2 = ( m 1 + m 2 ) v ′ m 1 v 1 + m 2 v 2 = ( m 1 + m 2 ) v ′
conservation of momentum along x-axis for 2D collisions m 1 v 1 = m 1 v ′ 1 cos θ 1 + m 2 v ′ 2 cos θ 2 m 1 v 1 = m 1 v ′ 1 cos θ 1 + m 2 v ′ 2 cos θ 2
conservation of momentum along y-axis for 2D collisions 0= m 1 v ′ 1 sin θ 1 + m 2 v ′ 2 sin θ 2 0= m 1 v ′ 1 sin θ 1 + m 2 v ′ 2 sin θ 2