Answer:
The change is momentum is given by ∆p=p(inital) - p(final) =4-2=2 kg.m/s
Step-by-step explanation:
momentum is the product of mass and velocity (speed)
So it's initial momentum would be:
p=mv=(1)(4)=4 kg.m/s
It's final momentum is given by:
p=mv=(1)(2)=2 kg.m/s