Question

At 13:20 on the last Friday in September, 1989 a frantic call was received at the local police station. There had been a serious automobile accident at the intersection of Main Street and State Street with injuries involved. Lt. John Henry arrived at the scene ten minutes after the phone call and found that two cars had collided at the intersection. In one car, the driver was unconscious and in the other car, both the driver and one passenger were injured.
After the emergency vehicles transported the injured to the hospital, Lt. Henry's responsibility is to investigate the accident in order to determine whether one of the drivers (or both) are responsible. With the severity of injury in this accident, the investigation is critical because there may be a fatality involved.

1. What questions does John Henry have to answer in this investigation? What measurements does he need to take? What data should he collect? What other information does he need to record in order to aid the investigation? What physics principles will John Henry need to use in order to help analyze the data and answer his questions?
2. If two cars moving at right angles to each other collide, in what direction do you expect the cars to be moving after the collision?
3. What factors will influence the direction and distance traveled after impact?

Answer 1

The kinematics and conservation of momentum relationships allow to find the results for the questions about the measurements and conditions to know the accident conditions are:

     1) The principles of conservation of momentum  and kinematics.

     2)  $\theta = tan^{-1} \frac{P_{01}}{p_{02}}$

     3) The factors that influence the direction and distance traveled are:

         The initial speed of the vehicles

         The mass of the vehicles

         Pavement conditions: dry, wet, humid, with dirt or loose sand.

1) Kinematics studies the movement of bodies, they look for relationships between position, speed and acceleration.

To analyze the accident, you must answer a question such as what speed the vehicles had before the accident, this is the initial speed of each one and their directions.

When reviewing the kinematics relationships we have.

        $v^2 = v_o^2 - 2 a x$  

Where the acceleration is given by Newton's second law.

        fr = m a

The friction force is given by the expression.

       fr = μ N  

       fr = μ mg

       

Let's Substitute.

         μ m g = m a

         a = μ g

The friction coefficient is tabulated, for different types of rubber, pavement and wet,  dry conditions, etc.

Therefore, the researcher must measure the braking distance of the vehicles, which can be taken from the mark of the tires on the road and note the condition of the pavement if it is dry or wet and the visibility of the day.

This is the speed of the vehicles just after the impact, using the law of conservation of momentum you can find the speed of the vehicles before the impact

        $p_o = p_f$ \f

         

Where this is a vector expression, which in general is solved with the components of each directional.

Consequently to answer the questions you must use the principles of conservation of momentum  and kinematics.

2) If the vehicles travel at right angles and their masses are similar, the direction after the collision  in each direction.

           $tan \theta = \frac{p_{01}}{p_{02}}$  

           $\theta = tan ^{-1} \frac{p_{01}}{p_{02}}$  

3) The factors that influence the direction and distance traveled are:

     The initial speed of the vehicles

     The mass of the vehicles

     Pavement conditions: dry, wet, humid, with dirt or loose sand.

In conclusion, using the kinematics and conservation of momentum relationships, we can find the answers to the question about measurements and conditions to know the accident conditions are:

      1) The principles of conservation of momentum  and kinematics.

     2)  $\theta = tan^{-1} \frac{P_{01}}{p_{02}}$

     3) The factors that influence the direction and distance traveled are:

         The initial speed of the vehicles

         The mass of the vehicles

         Pavement conditions: dry, wet, humid, with dirt or loose sand.

Learn more about kinematics and momentum here:   brainly.com/question/17304001