**Q:** An engine provides 5.0 kN of force to keep a 1600-kg vehicle moving at a uniform speed. (Air resistance is negligible.) What is the coefficient of rolling friction between the tires and the road surface?

**A:** First convert 5.0 kN to Newtons: **F = 5.0 kN = 5000 N**. (Just like 5 kg = 5000 grams when measuring mass.)

You know it’s traveling at uniform speed, so this tells us that the right force = left force. **There is no net force, because there is no acceleration!**

F = 5000 N

m = 1600 kg

g = 9.8

= ?

Use this equation:

and solve for .

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