Answer:
a) 
Explanation:
a) the cross-sectional area of the hose would be the square of radius times pi. And since the sectional radius is half of its diameter d. We can express the cross-sectional area A1 in term of diameter d1

Answer:
B. Kinetic energy of the system is partially used up in the deformation of the vehicles.
Explanation:
In an inelastic collision, momentum is conserved, but kinetic energy is not. Kinetic energy is lost as heat or lost in the deformation of the objects.