A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Need help A ball is thrown directly up in the air from a height of 5 feet with an initial velocity of 60 ft/s. Ignoring air resistance, how long until the ball hits the ground? Use the formula h=-16t^2+60t+5, where h is the height of the ball in feet and t is the time in seconds since it is thrown. Round your answer to the nearest tenth A. 2.1 seconds B. 3.8 seconds C. 2.4 seconds D. 1.8 seconds

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I say it's B not sure tho

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

    Yep b

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

    'm gonna give you a short way to do this Let us name our vectors! Anything going up is positive and anything coming down / acting down is negative. u = +60 ft/s g = -9.8 m/s^2 (since gravity acts downward) In this case though, it is m/s^2 and not ft/s^2....Change metres to feet and we will get -32.1522 ft/s^2 s = -5 ft (s is displacement which is vector and that is the direction the ball will be falling when coming down so we have taken into consideration direction). t = what we are looking for We can therefore use the equation: s = ut + 0.5at^2 We can modify ti to get: s = ut + 0.5gt^2 Plug in values: -5 = (60)t + 0.5(-32.1522)t^2 -5 = 60t - 16.0761t^2 FORM INTO A QUADRATIC EXPRESSION: -16.0761t^2 + 60t + 5 = 0 Solve for t by using the quadratic equation: You get t = -0.08 s (1 d.p) and t = 3.8 s TIME CAN NEVER BE NEGATIVE, so we will use the POSITIVE value for the time Hence, the time for trajectory (movement of the ball) is 3.8 seconds

  4. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

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.