Question

EXAMPLE 1.1 Headfirst into the snow Alice is sliding along a smooth, icy road on her sled when she suddenly runs headfirst into a large, very soft snowbank that gradually brings her to a halt. Draw a motion dia- gram for Alice. Show and label all displacement vectors. MODEL Use the particle model to represent Alice as a dot. VISUALIZE FIGURE 1.11 shows Alice's motion diagram. The problem statement suggests that Alice's speed is very nearly constant until she hits the snowbank. Thus her displace- ment vectors are of equal length as she slides along the icy road. She begins slowing when she hits the snowbank, so the displacement vectors then get shorter until she stops. We're told that her stop is gradual, so we want the vector lengths to get shorter gradually rather than suddenly. FIGURE 1.11 Alice's motion diagram Hits snowbank Stop This is motion at constant speed because the displacement vectors are a constant length The displacement vectors are getting shorter, so she's slowing down.

Answer 1