To accurately determine the speed of two cars before they collide, you would typically need access to certain data and information. Here are a few methods that can be used:
Witness Statements: Eyewitnesses who observed the accident can provide valuable information about the events leading up to the collision. They may be able to estimate the speeds of the vehicles involved based on their own observations. However, eyewitness accounts are subjective and may not always be entirely accurate.
Accident Reconstruction: Accident reconstruction experts can analyze various factors to estimate the speeds of the vehicles involved. They examine evidence such as skid marks, damage patterns, vehicle positions, and other physical evidence to reconstruct the events leading up to the collision. This process often involves the use of mathematical formulas, computer simulations, and other scientific techniques.
Event Data Recorders (EDRs): Some modern vehicles are equipped with event data recorders or "black boxes" that capture and store information about the vehicle's speed, acceleration, braking, and other parameters. If the vehicles involved in the collision have EDRs and they are accessible, the data from these devices can provide accurate information about the speeds of the vehicles before the collision.
It's important to note that accurately determining the speed of two cars before a collision can be a complex task. Different methods may have varying degrees of accuracy and reliability, and the availability of data and evidence will also play a significant role. Therefore, it is often necessary to consult experts such as accident reconstruction specialists to obtain the most accurate assessment of the speeds involved in a collision.