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Bullet Trajectory Overview
Bullet Trajectory Overview
Objective:
Objective:
By the end of this activity, you will be able to:
Determine the bullet trajectory given two reference points
Calculate the angle of elevation given two reference points
Estimate the location of a shooter using the law of tangents after analyzing sketches and measurements from a crime scene.
Introduction:
Introduction:
Recall the assignment yesterday, bullet trajectory notes. We discussed how investigators determine a bullet's trajectory. As a reminder, look at the diagram to the right!
Below you will practice analyzing bullet trajectory. For each problem submit your sketch and then your answer to the problem in the corresponding buttons. Show your work in your answer submission.
*Hint: you may work this out on paper and then submit a picture of the work OR you may complete this all digitally*
Figure 1 from Saferstein, R. (2010). Forensic science: An introduction (4th ed.). Prentice Hall.In this picture you see how to track the bullet’s trajectory, a line is drawn connecting two points along the bullet’s known path. These two points could be an entry wound (A) and exit wound (B) on a victim.The angle of elevation is the angle created by the bullet’s trajectory and the horizon. To determine the angle of elevation, draw a horizontal line (parallel to the horizon) that intersects the trajectory, and measure the angle formed by these two lines.
Problem 1
Problem 1
A witness saw a victim fall while riding his bike. The cyclist had been struck in the head by a bullet. When the crime-scene investigators arrived, they estimated the angle of elevation of the shooter to be about 13 degrees based on the hole in his helmet and the entry wound on his head. The distance from his head to the building where the bullet was fired was 76 feet. The height from the ground to the entry wound on the victim while on his bike measured 3 feet above the ground.
Based on this information, what is the distance from ground level to the window where the bullet was fired? Use the law of tangents to calculate your answer.
Problem 2
Problem 2
A person stood on a high platform and shot a target below in the bull’s-eye. The center of the target was 60 feet away from the platform. The target stood 40 inches from the ground. The angle of the shot was 10 degrees. How high up (in feet) was the shooter located on the platform?
Problem 3
Problem 3
A bullet was found in a car's driver's seat parked next to a hotel. The bullet went through the car's windshield and was embedded in the car seat. Two reference points: bullet hole in windshield, and bullet hole in seat. From the two reference points, investigators calculated a 22 degree angle of impact. Then it was determined that the hotel was approximately 360 inches from the car headrest. (Headrest was 12 inches from the ground). How high was the shooter when the gun was fired in inches?
Submit in the button above.
Conclusion
Conclusion
Compare determining trajectories from two fixed objects such as a hole in a wall and a hole in a window to determine the trajectory of a bullet from entrance and exit wounds. Why would the evidence of bullet trajectory be less reliable based on entrance and exit wounds sustained by a victim as opposed to entrance and exit holes in walls or windows?
Describe the significance of determining the trajectory of a projectile when trying to solve a crime.
During autopsies, bullets needs to be recovered and submitted to police as evidence. Investigators have been known to drag rivers to recover a firearm. Describe the type of evidence that could be recovered from firearms, bullets and cartridge casings that could help link evidence to a particular firearm or person.
List problems that might interfere with the accuracy of your results.
What problems would be encountered if we couldn’t accurately determine the trajectory angle?
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