Teacher Notes



Teacher Notes
Publication No. 12493
Flinn Forensic Files—BallisticsStudent Laboratory KitMaterials Included In Kit
Bullet 1 card, 3
Bullet 2 card, 3 Bullet 3 card, 3 Rulers, 15cm, 9 Shoe print 1, 3 Shoe print 2, 3 Shoe print 3, 3 Tape measure Additional Materials Required
(for each lab group)
Calculator, scientific Tape measures Prelab PreparationBullet 1/Suspect 1
Safety PrecautionsThis laboratory activity is considered nonhazardous. Please follow all laboratory safety guidelines. DisposalAll materials can be saved for future use. Lab Hints
Teacher Tips
Correlation to Next Generation Science Standards (NGSS)^{†}Science & Engineering PracticesUsing mathematics and computational thinkingObtaining, evaluation, and communicating information Developing and using models Analyzing and interpreting data Disciplinary Core IdeasHSPS2.A: Forces and MotionCrosscutting ConceptsPatternsCause and effect Systems and system models Performance ExpectationsHSPS21. Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration. Answers to Prelab Questions
Sample Data{12493_Data_Table_1}
{12493_Data_Figure_8}
Answers to Questions
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Student Pages


Student PagesFlinn Forensic Files—BallisticsIntroductionOne bullet hole can help solve a crime! Determine the height of a suspect based upon the bullet trajectory. Concepts
BackgroundCase Background Sin = opposite/hypotenuse {12493_Background_Figure_1}
For example, if the minor axis is 13 mm long and the major axis is 19 mm long (see Figure 2), what is the angle of impact?
{12493_Background_Figure_2}
Sin (i) = length of minor axis/length of major axis Now that the impact angle has been calculated, the location of the shooter can be determined by using the properties of right triangles. The three interior angles of a triangle must always add up to 180°. One of the angles will be 90°, representing the angle between the floor and the wall. Therefore, if the second angle (the impact angle) is determined from the elliptical bullet hole left in the wall the third angle can be calculated. Using the impact angle calculation above, angle A is 43° and angle B is 90°, which is the angle between the wall and the floor. Since all three interior angles must add up to 180° the unknown angle can be calculated, 180 – 90 – 43 = 47°. Angle C is known as the angle of elevation or angle of depression. If the bullet hole is higher than the shooter’s shoulder it would be an angle of elevation, if it is lower it is known as an angle of depression. {12493_Background_Figure_3}
In this case, the bullet hole is in the wall at 93" above the floor. The height of the suspect is 6'3" (75") assuming the suspect’s head is 8" tall the shoulder height of the suspect would be 5'7" (67"). Since the bullet hole is above the shooter’s shoulder, the angle from the shooter would be considered an angle of elevation. With this information we can determine the distance the shooter was from the wall when the bullet was fired. The length of side a would be calculated by subtracting the height of the suspect’s shoulder from the height of the bullet: 93" – 67" = 26". The length of segment a is 26" and the angle of elevation is 43°. The tangent function can now be used to determine the length of b. Tan = opposite/adjacent (see Figure 4).
{12493_Background_Figure_4}
See the following equation.
Tan (47) = 26/b Experiment OverviewThe police received an anonymous call from someone who said they heard shots being fired in an abandoned warehouse outside of town. They said it seemed like the shooters were conducting target practice. Police arrived and the shooters had left. However, there was evidence left behind. There were footprints in the dirty floor and bullet holes in the wall. Police found three different footprints and the crime scene has been reconstructed for each of the three suspects. Calculate the height of the suspects based upon the reconstruction of the crime scene. Materials
Calculator, scientific
Crime scene simulations Ruler, 15cm Tape measure Prelab Questions
Safety PrecautionsThis laboratory activity is considered nonhazardous. Please follow all laboratory safety guidelines. Procedure
Student Worksheet PDF 