Two 100-kg bumper cars are moving toward one another in opposite directions, Car A at 5 m/s meters per second, and Car B at −9 m/s negative 9 meters per second. They collide head-on with one another. Each car bounces back in the opposite direction it was moving before the collision. If after the collision the final velocity of Car B is 5 m/s meters per second, what is the final velocity of Car A?

On a mild saturday morning while people are working inside, the furnace keeps the temperature inside the building at 23degreesc. at noon the furnace is turned off, and the people go home. the temperature outside is a constant 16degreesc for the rest of the afternoon. if the time constant for the building is 3 hr, when will the temperature inside the building reach 18degreesc? if some windows are left open and the time constant drops to 2 hr, when will the temperature inside reach 18degreesc?