Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

applesjgtl

A 1200 kg racecar is driven along a frictionless horizontal surface at a speed of 65 km/hr. If a horizontal cord brings the car to rest in a distance of 2.2 m, what is the elasticity constant (k) of this spring?

  • one year ago
  • one year ago

  • This Question is Closed
  1. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    Do you have any idea where to start?

    • one year ago
  2. applesjgtl
    Best Response
    You've already chosen the best response.
    Medals 0

    Not really.

    • one year ago
  3. applesjgtl
    Best Response
    You've already chosen the best response.
    Medals 0

    65km/hr=18.06m/s

    • one year ago
  4. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    I'd start by converting the velocity to m/s. Then calculate the KE of the racecar using:\[KE=\frac{1}{2}mv^2\]

    • one year ago
  5. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    Since the racecar comes to a rest you know that the change in KE will be the amount of work done on the car and: \[W=\frac{1}{2}kx^2\]

    • one year ago
  6. applesjgtl
    Best Response
    You've already chosen the best response.
    Medals 0

    1/2(1200kg)(18.06m/s)^2=195698.16J

    • one year ago
  7. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    So:\[KE=\frac{1}{2}(1200kg)(18.06m/s)^2=195698J=Work\space done\]\[195698J=\frac{1}{2}k(2.2m^2)\]Now just solve for k.

    • one year ago
  8. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    Small correction there...it should have been:\[195698J=\frac{1}{2}k(2.2m)^2\]

    • one year ago
  9. applesjgtl
    Best Response
    You've already chosen the best response.
    Medals 0

    Oh, because it's not the unit that's being squared.

    • one year ago
  10. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    Yep

    • one year ago
  11. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    Looking at that last equation, what do you get for k?

    • one year ago
  12. applesjgtl
    Best Response
    You've already chosen the best response.
    Medals 0

    k=80867.01

    • one year ago
  13. applesjgtl
    Best Response
    You've already chosen the best response.
    Medals 0

    What's that unit?

    • one year ago
  14. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    It's a constant...no unit. You also have to consider significant figures in your calcs but that's how you solve it.

    • one year ago
  15. applesjgtl
    Best Response
    You've already chosen the best response.
    Medals 0

    Not overly concerned with significant figures in this case, but you make a good point. Thanks!

    • one year ago
  16. Shane_B
    Best Response
    You've already chosen the best response.
    Medals 1

    no problem :)

    • one year ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.