diff --git a/docs/ce1/ece105.md b/docs/ce1/ece105.md
index 8254f68..413af55 100644
--- a/docs/ce1/ece105.md
+++ b/docs/ce1/ece105.md
@@ -27,3 +27,11 @@ Please see [SL Physics 1#2.3 - Work, energy, and power](/g11/sph3u7/#23-work-ene
 ## Momentum and impulse
 
 Please see [SL Physics 1#2.4 - Momentum and impulse](/g11/sph3u7/#24-momentum-and-impulse) for more information.
+
+The change of momentum with respect to time is equal to the average force **so long as mass is constant**.
+
+$$\frac{dp}{dt} = \frac{mdv}{dt} + \frac{vdm}{dt}$$
+
+Impulse is actually the change of momentum over time.
+
+$$\vec J = \int^{p_f}_{p_i}d\vec p$$