As heat is added to water, is it possible for the temperature measured by a thermometer in the water to remain constant?

Aboat that travels with constant speed of 6.10 m/s in still water is to go directly across a river. the current in the river flows at 1.95 m/s. (a) at what angle must the boat be steered?

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 • what must the total momentum of the system be after the train cars collide?   kg •  

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.