1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Find angle and seconds

  1. Feb 16, 2017 #1
    1. The problem statement, all variables and given/known data
    A football punter can punt a maximum range of 40.8 m. If he instead wants to punt only 34.6 m, but maximize the time the ball is in the air, at what angle from the horizontal should he kick the ball, and how long will it stay in the air if he hits it perfectly? (neglect air resistance) Assume he can kick the ball with the same force every time.

    2. Relevant equations
    • R = (u2sin 2θ) / g
    • Rmax = u2/g

    3. The attempt at a solution

    I used the above equations to solve the problem but I'm getting 29.0 degrees and 1.98 seconds. When I try to submit my answers says it's wrong. Do I have the right sig figures or it just something wrong on my calculations
  2. jcsd
  3. Feb 16, 2017 #2


    User Avatar
    Homework Helper
    Gold Member
    2017 Award

    Hello and welcome to PF!

    Consider the possibility that there might be more than one mathematical solution to your equations. In particular, the inverse sine function on your calculator probably only gives you the "principal value". For example, my calculator tells me sin-1(0.5) is 30 degrees. It misses the fact that sin(150o) is also 0.5.
  4. Feb 16, 2017 #3
    Why don't you show your calcs.

    What if he kicked it at 90 degrees?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted