Jump to content
Sign in to follow this  
Guest erockest3

Car Crash Web Quest

Recommended Posts

Guest erockest3

Car Crash Web Quest

A traffic accident occurred in a 35 km/hr speed limit zone on Millway Street in which a 3000-kg Cadillac Escalade SUV rear-ended a 2000-kg Subaru Outback Wagon that was stopped at a stop sign. Because the entire police investigative division has gone on vacation to Bora Bora to relax, the mayor has contracted my team of experts to determine what happened and what traffic laws were broken. Using the little bit of data we were supplied we were able to find out enough information to figure out if the driver of the 3000-kg Cadillac Escalade SUV was speeding.

Using our kinematics equations we used the formula Vf^2 = Vi^2 + 2ad to figure out the velocity of both the Wagon and the SUV. Using the skid marks we were able to determine the distance and we were given acceleration. On top of that we knew the final velocity had to be zero because the cars came to a complete stop. Using what we knew we solved for Vi and found that the SUV’s initial velocity was 2.8 m/s and the wagon’s initial velocity was 12 m/s. Since we found the velocity of both vehicles and the masses were given we were able to use the equation mv = p to calculate the momentum of both immediately following the collision. We found that the momentum of the SUV equaled a total of 8,400 kg*m/s and the wagon equaled 24,000 kg*m/s. Knowing that the momentum before the collision has to be equal to the momentum after the collision we were able to find the momentum of each vehicle immediately before the collision. We added up each cars momentum from after the collision and got a total of 32,400 kg*m/s but, because the wagon was sitting at a stop sign it had no momentum therefore the SUV had a momentum of 32,400 kg*m/s.

After finding the momentum of the cars before the collision we used the equation mv = p to calculate the speed/velocity before the cars collided. Using the given mass of 3000kg and the momentum of 32,400 kg*m/s we found the speed/velocity was 10.8 m/s for the SUV. The speed of the wagon had to be 0 because it was sitting still at the stop sign. Using what we know about conversions we were able to convert 10.8 m/s to km/hr finding out that the SUV was going 38.88 km/hr which was three km/hr over the speed limit. Therefore the SUV was indeed speeding.

Developed by: Eric, Rashi, and Ryan

Edited by erockest3

Share this post


Link to post
Share on other sites
Guest GuitarGirlx3

A car crash occurred in a 35 km/hr speed limit area on Millway Street in which a 3000-kg Cadillac Escalade SUV collided into a 2000-kg Subaru Outback Wagon that was at a stop sign.

We needed to determine whether or not the SUV was speeding or not. We gathered an auto expert, collision expert, and investigator to collect the data needed to find out what happened. First, we listed the variables that were given, such as the speed limit, the mass of the vehicles, the accelerations, and the distance that the automobiles skidded.

The acceleration of the SUV was -2m/s2, and for the wagon, it was -3m/s2. The distances of the skid marks were 2m for the SUV and 24m for the wagon. Then, we used kinematic equations to solve for the final and initial velocities of both vehicles. The initial velocity for the SUV was 2.83 m/s, and 12m/s for the wagon. We used the formula vf2=vi2+2ad, modified into vf2-2ad=vi2 in order to get the initial velocities. The final velocity for both was 0 because they stopped. Next, we needed to determine the momentum of the automobiles, so we created a Momentum Table.

[TABLE="align: left"]

[TR]

[TD]Objects

[/TD]

[TD]Pb kgm/s

[/TD]

[TD]Pa kgm/s

[/TD]

[/TR]

[TR]

[TD]SUV

[/TD]

[TD]3000V

[/TD]

[TD]8490

[/TD]

[/TR]

[TR]

[TD]Wagon

[/TD]

[TD]0

[/TD]

[TD]24000

[/TD]

[/TR]

[TR]

[TD]Total

[/TD]

[TD]3000V

[/TD]

[TD]32490

[/TD]

[/TR]

[/TABLE]

According to the Law of Conservation of Momentum, Pb=Pa, therefore 3000V=32490, and we solved for V, getting an answer of 10.83 m/s. So, that data had to be converted into km/hr, which was 38.988 km/hr. The momentum table helped us determine the momentum before and after the two vehicles collided. To get Pa, we used the equation P=mv (momentum, P, = mass times velocity), which was (3000kg) (2.83m/s) =8490 kgm/s. And for the wagon, it was (2000kg) (12m/s) =24000kgm/s. The Pb for the SUV was its mass times the velocity, which we needed to find, and for the wagon it was 0. The speed of the SUV before the collision was 38.988 km/hr and for the wagon, it was 0.

Furthermore, the SUV was speeding at 38.988 km/hr, between 3 and 4 km/hr over the speed limit, which was 35 km/hr.

Developed by: Lianna, Harley and Ben

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

Terms of Use

The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.

Copyright Notice

APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to info@aplusphysics.com. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.

×
×
  • Create New...