S

Stopping Impulse

Scaling a car crash

STEM ACTIVITY #1 Objective: You will use a motion sensor to gather data to investigate

the relationship between stopping force and time of impact.

Materials : motion sensor, skateboard, wall, bathroom scale, Excel spreadsheet

Using Data Studio Software, create two collisions into a wall. One will bring you to a slow stop, and the other should employ a moment of collision that models a faster stop. Create a velocity time graph for each and replicate these into your lab books. You may screen shot and print these ( 3-4 to a page please!) Play around until the graphs have a look that makes sense. To hit the wall at a consistent speed, use the bathroom scale method of applying force. Remember, the “push” force is not the same as the “stopping” force.

Sample collision

m/s

s 1. Notice that we are interested in the part of the graph where the wall applies the impulse (i.e. takes the velocity from some value to zero).

2. The motion sensor chooses your direction as negative. It is truly arbitrary

3. Using the mouse, zoom in on your graph to enlarge the portion of interest

Data Portion

s 1. The slope of your graph is m/s/s which is acceleration

2. Slope time mass = F!3. Keep track of the time

at which the force occurs

1. Create a table to keep track of the key variables that apply to impulse2. Calculate the Force required to stop you in your 2 scenarios using your knowledge of Impulses. Show your equation and work.3.Calculate the instantaneous force from three points on your graph.

4.Create a F x t graph in your lab book from step #3, and use it to mathematically calculate the Impulse applied to stop you in these scenarios.

m/s m/s

a a

Conclusion Your crash is a “scale model” for a car crash. The

average car has a mass of 1,100 kg ( about a metric ton). Use your data to calculate how much force (Newtons) would be generated on the front end of a real car ( to scale) if the event occurred as you have graphed it. Do it for both crashes.

Using a concluding Paragraph…..

1. Explain what your goal was for this lab

2. How does your data apply tot real car wreck

3. What played the role of a bumper in this lab. Is this realistic?

4. List 3 ways you can manipulate any of the 4 variables in this lab too improve your chances of surviving a car wreck