IMPULSE (CHANGE IN MOMENTUM)

When a force acts on an object for a period of time, it will change the object's momentum.
This quantity (change in momentum, or the product of force and time) is called IMPULSE.
We can easily derive a formula from Newton's second law. F=ma
a=Δv/Δt so F=m Δv/Δt
gives FΔt=mΔv
mΔv is the change in momentum, Δρ
In your textbooks the formula is given as FΔt=Δρ.