Linear Momentum (Momentum, Impulse and Collisions) Helpful equations Deﬁnitions Force vs. Time graph F- Force (N) p- momentum (kg*m/s) m- mass (kg) v- velocity (m/s) j- impulse (N*s) t- time (s) Subscripts Σ- sum of all net- sum of all ∫- Integral Δ- change in ➝- vector Inelastic collision An Inelastic collision is when Kinetic energy is not conserved and the colliding objects stick together. In this scenario the two cars stick together after they collide. Practice problem This is a graph of the force vs. time relationship. Since impulse is the integral of force with respect to time, the area under this graph will be the impulse. Recoil Problem This is an example of a recoil problem. What characterizes this example as a recoil problem is that the total momentum of the system begins at zero and then the object splits into two pieces that travel in opposite directions. To solve problems like these simply set the net momentum equation equal to zero.