When a car is allowed to coast on a level road it slows down and stops. is this a violation of newtons first law of motion?

Answer 1

No it is not because there is a friction force opposing the car's forward motion and this is what makes it slow down and stop.

There is friction in the tires because they are compressed and released as each part of the tire touches the ground. There is friction in the wheel bearings, and there is the friction of the wind on the front of the moving car.

Compare this with a planet in space with has virtually no friction opposing its forward motion so that it is able to continue for possibly billions of years.

Answer 2

No, the car decelerates until it stops because an outside force is acting against its inertia: the friction between the tires and the road, in the wheel bearings, and in the transmission (there is also air resistance, but it is negligible in this case).

Answer 3

To anybody watching it, it sure looks like it. That's why we have such a hard time accepting Newton's first law (among others).

When you really think about Newton's first law, a few things that it tells you are:

• A moving object doesn't need any force on it to keep moving.
• If there are no forces acting on a moving object, it keeps going at a steady speed.

These go completely against every thing we ever see in daily life. Our brains tell us

• A moving object needs force on it to keep moving.
• If there are no forces acting on a moving object, it stops.

When you see car coasting on a level road slow down and then stop, you say to yourself "Self ! That's how it's supposed to work. Newton's First Law does not hold water."This statement is the one that 'feels' right, and matches everything we ever see. Newton's first law is the statement that feels weird and suspicious. The coasting car appears to violate Newton's first law, because we don't take account of the losses of kinetic energy due to various frictions, including air resistance.

Answer 4

No, because the conditions for the First Law are not met.