Consider a system to be two train cars traveling toward each other. What is the total momentum of the system before the train cars collide?

kg • m/s

What must the total momentum of the system be after the train cars collide?

kg • m/s

explanation:

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

answer( increase) their individual contractile activity;