Embedded Files
Introduction:
This is a capstone lab that challenges students to apply what they have learned about one dimensional constant acceleration motion, forces, Newton's Laws, and unit conversion. The students act as auto accident investigators who, after studying a model of an accident scene, use physics to determine if the driver of the vehicle involved was speeding and/or negligent.
What Happens:
There are four major parts to this lab:
1) Students use a "skid sled" to determine the coefficient of kinetic friction between rubber and the road.
2) Students make careful measurements of the accident model which (along with the friction coefficient) allow them to calculate the initial velocity of the vehicle and the reaction time of the driver.
3) Students take part in the "Reaction Time Minilab" to determine the average reaction time of an undistracted driver.
4) Students collectively write "crash narratives" that communicate their conclusions and discuss how those conclusions were reached.
What it Looks Like:
What You Need:
SKID SLED:
• Brick
• Spring scale (~30N capacity)
• Mousepad with rubber underside
• Duct tape
• String
ACCIDENT MODEL:
• Road surface printout (file included below)
• Strip mall facade printout (file included below)
• Scale man printout (file included below)
• Cardboard - A flat rectangle approximately 1 meter by 0.5 meters, plus scrap cardboard (or small cardboard boxes) to build the strip mall
• Matchbox car
• Paperclip (bend and tape to the back of the scale man printout--see detail image.)
• Cellophane tape
• Gluestick
REACTION TIME MINILAB:
• Dual-photogate timing device (we use these)
• Ringstand & clamps
• Cardboard strips & masking tape (tape these to students' shoes so that they can "break" the photogate beam with their foot when applying the "brake.")
• Cellphones & MP3 Players (students bring these themselves)
STUDENT HANDOUTS:
(All files included below)
• Auto Accident Reconstruction Student Handout (two versions are provided with varying degrees of structure provided)
• Investigator's Notepad (for uniform/organized data collection)
• Rection Time Minilab student handout
Time Required:
Traditionally my level one students are able to complete all aspects of this lab (except for writing the report) in approximately three and a half 50 minute class periods. My level two students usually require four and a half class periods. Expect to spend around an hour total building the model and the skid sled.
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