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 car weighing 1400kg accelerates from 90 km/hr to 110 km/hr in 6.0s. a) assuming no friction, what was the power output of the car? b) If a frictional force of 700 N acted on the car over a distance of 400 m during the same 6.0-second acceleration, what would be the power output of the car if the same speed increase was observed?

  • one year ago
  • one year ago

  • This Question is Closed
  1. wio
    Best Response
    You've already chosen the best response.
    Medals 2

    Figure out it's change in kinetic energy.

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

    You have the mass and two velocities. So calculate the kinetic energy before and after acceleration.

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

    Power is just going to be energy / time

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

    kinetic energy is 1/2 mass * velocity^2

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

    You probably want to convert units to m/s

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

    Multiply by 1000 and divide by 3600?

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

    Yes

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

    For b) " 700 N acted on the car over a distance of 400 m" Just remember that work = force * distance that will tell you how much energy was taken away

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

    so subtract that out and calculate the power again.

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

    @applesjgtl got it?

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

    For part a, what value do I use for energy? Is it KE2-KE1?

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

    @wio, still there?

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

    For part a) use energy

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

    then divide the change in energy by time to get power output.

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

    Here's what I have

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

    Oh, I get it. Thanks for your help!

    • 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.