zdeams asked in Science & MathematicsPhysics · 7 years ago

Ok so I did this lab, which is due on friday (which sucks because finals are this week), and I am confused on four of the questions and would reallyyyy appreciate some help (two are below because i accidentally deleted two on my previous question)

1. In a 50 km/h head-on crash test, the steering column of passenger car 1 moved 3 cm upward and 2 cm rearward. The steering column of passenger car 2 moved 6 cm up and 24 cm toward the rear of the car. Which of the two cars would protect people better in a crash? Explain.

2. Why does a properly adjusted head restraint help prevent head and neck injuries to occupants in rear-end collisions? Explain your answer in terms of the law of conservation of momentum.

Relevance
• 7 years ago

A car in motion tends to remain in motion until a tree at rest tends to remain at rest.

1. The steering column which moved the least is the one less likely to enter the drivers chest--ordinarily. (The driver tends to remain in motion until restrainedassuming a seat belt non airbag)

Ordinarily one would compute a vector to determine direction and distance. This is a solving for a hypotenuse /right angle triangle problem. On face value the column moving the least is safer. The 6/24 would hit the upper chest, face, or possibly break the neck.

2, The injury the headrest prevents is "whiplash". In a rear collisionm the front car is driven forward under heavy Gs but the head on the neck has stationary inerta( at rest) and will tend to stay in the same location as the body moves from under it unless the head rest keeps the neck aligned with the body and prevents the snapback. As the car seat is moving from under the head the head would appear to snap back over the car seat causing both soft tissue damage--neck sprain with a possibility of breaking the neck. The take away for this question is understanding the inertia of the head which tends to remain at rest. The conservation of momentum is that a head at rest tends to remain at rest until acted on by a force--that of the body snatching it rapidly forward.

• 3 years ago

except i'm lacking something here, i could do it like this. bear in mind that... P = m v complete mass = mass of vehicle + mass of motive force = 1500 + ninety = 1590kg v = 60 km/h = 60000 / 3600 m/s = sixteen.sixty seven m/s P = 1590 * sixteen.sixty seven = 26505 kgm/s