Friction is a force, and from physics you know that forces can change the speed or direction of an object. The force of friction from dry pavement on your tires is much greater than the force of friction from snow or ice. why? Because ice creates much less friction with your tires than dry pavement.
But how does this lack of friction affect how your car is driven? Essentially, changes in speed and direction take much longer time and distance on ice or snow than on dry roads. The clearest example of this is slowing to a stop at a traffic light. In icy conditions, this stopping distance can increase by four times or more due to reduced frictional force. Changing speed isn’t just about slowing down either. You may have noticed that acceleration is also harder in icy conditions.
How about going around a curve? A car turning around a curve changes its direction, and forces are necessary to bring about that change. Usually the only acting force available to take a car around a curve is the force of friction. So if you reduce the friction force by making the road icy, you can’t change the direction of your car that fast. You have to drive more slowly around the bend or your car will slide out.
So far, the other forces present in the car have been ignored. For example, the force of gravity can affect the movement of your car on a hill. If you are going down a slope, part of the gravity is accelerating you. If you’re heading uphill, part of the gravity tends to slow you down. Either way, you need the force of friction to counteract these effects. Sometimes icy roads don’t have enough of this friction, which is why going up a steep hill or controlling the car’s speed while going down the slopes in these conditions can be difficult.
Forces don’t just affect the movement of your car on an icy road. From the motion of a soccer ball in the air to the motion of planets around the stars, forces affect all kinds of motion. By studying physics, you learn a lot about the relationship between force and motion. And if you understand the relationship between force and motion, you will understand a lot about the universe in which you live.
