1. A heavy crate rests on the bed of a flatbed truck. When the truck accelerates, the crate remains.

1. A heavy crate rests on the bed of a
flatbed truck. When the truck accelerates, the crate remains where it is on the
truck, so it, too, accelerates. What force causes the crate to accelerate?

2. Why is the stopping distance of a truck
much shorter than for a train going the same speed?