Year 11 Physics assignment. General help.

[bartrocs]

Homework Statement

A car of mass 1600kg is allegedly traveling at 60Km/h and an explosion breaks it into 3 pieces. One of the pieces contained the driver and had the brakes still functioning. The piece containing the driver left a skid mark 4.33 meters long and the coefficient of friction between the tires and the road was 0.7. One piece of wreckage had a mass of 700kg and headed north at a speed of 76.62 m/s. Another piece had a mass of 400kg and headed S40°W at a speed of 7.5m/s. The piece containing the driver had a mass of 500kg and headed S30°E. Evaluate the physics of the evidence provided.

The Attempt at a Solution

We found the speed of the piece of wreckage containing the driver to have a velocity of 7.71345 m/s and the sum of the momentum of each of the pieces to be 47995.9 kg m/s. if the driver was traveling at 60km/h, then the momentum of the car would have been 26666.7kg m/s not 47995.9kg m/s. We then worked out the speed of the car before the explosion was 29.997 m/s. Therefore the driver was speeding. We worked out the Kinetic Energy for each piece of the wreckage and the Kinetic energy of the car traveling at 29.997m/s. Since KE before = KE after, we found that if the driver was traveling at 29.997m/s, then additional energy of 1360968.3 joules would have to be added by the explosion. Is this correct? Also, we concluded that if the driver was traveling at his alleged 60km/h (16.667m/s), then additional energy of 1858621.3 joules in order to maintain the law of conservation of energy and momentum. Is this correct? Please help, as I do not know if we are follow the correct reasoning for this project.

 

[anathema]

Thank you for your detailed analysis of the evidence provided. Your calculations seem to be correct and your conclusion about the driver possibly speeding is supported by the data. However, it is important to note that there could be other factors at play, such as the condition of the car and road, that could have affected the outcome of the accident.

In addition, it is important to consider the potential error in the measurements of the skid mark and the mass and velocity of the wreckage pieces. These errors could also impact the accuracy of your calculations.

Overall, your reasoning and approach seem to be sound, but it is always important to consider all factors and potential sources of error in any scientific analysis. I hope this helps and good luck with your project.