J — impulse (N·s) F — force (N) Δt — contact time (s) Δp = mv_f − mv_i
Impulse J = FΔt = Δp
0.0 N·s
= Δp
Object
m · mass2.0 kg
vᵢ · initial velocity+3.0 m/s
Force Applied
F · force+10.0 N
Δt · contact time0.50 s
pᵢ = mvᵢ— kg·m/s
Δp = FΔt— kg·m/s
pf = pᵢ + Δp— kg·m/s
vf = pf / m— m/s
J = FΔt = Δp (impulse-momentum theorem)
same J: large F short Δt, or small F long Δt
airbags increase Δt → reduce F on driver
direction of F determines sign of Δp
J = FΔt = Δp: a force applied over time changes an object's momentum. The impulse equals the change in momentum. Adjust F and Δt and watch how the final velocity changes.