As a civil engineer for your city, you have been assigned to evaluate the purcha

Question

As a civil engineer for your city, you have been assigned to evaluate the purchase of spring-loaded guard rails to prevent cars from leaving the road. In response to a request for proposals^*, one company states their guard rails are perfect for the job. Each section of their guard rails consists of two springs, each having a force constant 3.13400 times 10^5 N/m with a maxim mum distance of compression of 0.614 m. (According to the manufacturer, beyond this compression the spring loses most of its ability to absorb an impact elastically.) The largest vehicle the guardrails are expected to stop are trucks of mass 5050.000 kg. What is the maximum speed at which these guard rails alone can be expected to bring such vehicles to a halt within the stated maximum compression distance? (Assume the vehicles can strike the guard rail head on and that the springs are perfectly elastic.) Number m/s Given your result, which section of road most often features such a speed? School zone Large avenue Highway Guard rails are pointless if the acceleration they create seriously injures passengers. One important safety factor is the acceleration experienced by passengers during a collision. Calculate the magnitude of the maximum acceleration of the vehicle during the time in which it is in contact with the guard rail safe in regards to acceleration? Yes No In the plot of acceleration as a function or distance which of the four curves most closely represents the acceleration exhibited by the car while colliding with the guard rail assuming ideal springs)? A B C D

Explanation / Answer

When spring are in parallel,

Keq = k1 + k2 = 2 k = 6.268 x 10^5 N/m

Applying energy conservation,

m v^2 /2 = keq x^2 /2

(5050) v^2 = (6.268 x 10^5) (0.614^2)

v = 6.84 m/s ..........Ans

Ans: School Zone

Applying vf^2 - vi^2 = 2 a d

0^2 - 6.84^2 = 2 (a) (0.614)

a = 38 m/s^2

a (in g's) = 3.9 g

So yes, it is safe.

Ans: Yes

a = F / m = k x / m

hence a and x are directly propotional.

Ans: C

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.