Use Newton's second law to determine the acceleration being applied to the sled. There are three forces at work on the sled (its weight, the force normal to the ground, and friction) but two of them cancel, leaving friction as the only effective force. This vector is pointed in the opposite direction of the sled's movement, so if we take the direction of its movement to be the positive axis, we would find the acceleration due to the friction to be
Now we use the formula
to find the distance it travels. The sled comes to a rest, so , and let's take the starting position to be the origin. Then the distance traveled is
Answer: Greenhouse gases affect how much of the Sun's energy the Earth loses back to space. Predicting global temperature change is hard, even though the principle sounds easy. In simple terms, energy reaches Earth from the Sun.