Thanx for everyone who has helped so far. (This is not homework, I'm doing problems to study for my final that is in less than 3 hours). This next question i'm having a hard time with is... A 2150-kg truck is traveling along a straight,level road at a constant speed of 55.0km/h (15.8m/s) when the driver removes his foot from the accelerator. After 21.0 seconds, the truck's speed is 33.0 km/h (9.2m/s). What is the magnitude of the average net force acting on the truck during the 21.0 second interval? The answer is 626 N but I have no idea on how to get to it.