Serway & Jewett — Linear Momentum and Collisions: Problem 19

You have been hired as an expert witness by an attorney for a trial involving a traffic accident. The attorney’s client, the plaintiff in this case, was traveling eastbound toward an intersection at $13.0\text{ m/s}$ as measured just before the accident by a roadside speed meter, and as seen by a trustworthy witness. As the plaintiff entered the intersection, his car was struck by a northbound driver, the defendant in this case, driving a car with identical mass to the plaintiff’s. The vehicles stuck together after the collision and left parallel skid marks at an angle of $\theta = 55.0^\circ$ north of east, as measured by accident investigators. The defendant is claiming that he was traveling within the $35\text{-mi/h}$ speed limit. What advice do you give to the attorney?