Ian Graham 
Forces and Motion [PDF ebook] 
Investigating a Car Crash

An unfamiliar noise stops shoppers in their tracks: cars and a truck are crashing into each other. Fortunately no-one is hurt seriously, but what has caused the accident? This book looks at the topics of forces and motion to explain about speed, acceleration, friction, and momentum. It shows how investigators can use their knowledge of science and technology to sift through the evidence to determine the cause of the crash.