Which car is harder to stop and why?
calculate the momentum of cars a and b, and then
answer the question
car a:
mass: 1,000 kilograms
velocity: 40 meters/second
car b:
mass: 4,000 kilograms
velocity: 10 meters/second

The momentum of bath cars is 40000 Ns which make the difficulty to stop each car in aspect of fprce is the same.

Explanation:

Momentum (P) =mass(m) × velocity (v)

For car A,

                    P = m × v = 1000 × 40 = 40000 Ns

For car B,

                    P = m × v = 4000 × 10 = 40000 Ns

Force (F) = Momentum change(ΔΡ)/ time taken(t)

            F = ΔΡ/t

When stopping the car the momentum changes from 40000 Ns to 0

So momentum change in both cars is the same. So to stop the two cars in a  given time (t) you need the same force, which means you will feel same difficulty.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)