math

posted by .

ball is thrown up at 88 ft/s from a height of 25 feet. Path of ball is
y = -16t^2 + 88t +25. y is the height of ball above the ground t seconds after being thrown. when does it reach maxiumum height? (I got that at 2.75 s)

At what time does the ball hit the ground? (I set equation to =0, but I got 5.2 s and answer is 5.77 s)

  • math -

    Vf = Vo(t) - 32(t)
    Vf = 88 - 32t or t = 2.75sec.

    Height reached from 25 ft. height
    h = 88(t) - 32(t^2)/2
    h = 88(2.75) - 16(2.75)^2 = 121 ft.

    It takes the same 2.75 sec. to return to the original launch height of 25 feet and an increment more to fall the 25 feet further to the ground.

    Therefore,
    h = Vo(t) + 32(t^2)/2
    (121 + 25) = 0(t) + 16(t^2)
    t - sqrt(146/16) = 3.02

    The time from launch to impact is therefore (2.75 + 3.02) = 5.77 sec.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. phy

    A blue ball is thrown upward with an initial speed of 20.6 m/s, from a height of 0.8 meters above the ground. 2.5 seconds after the blue ball is thrown, a red ball is thrown down with an initial speed of 8.2 m/s from a height of 23.7 …
  2. Algebra

    If a ball is thrown vertically upward from a height of 56ft. above ground with an initial velocity of 40ft. per second, then the height of the ball above ground t seconds after it is thrown is given by f(t)=-16t^2 + 40t +56. How many …
  3. college

    A blue ball is thrown upward with an initial speed of 19.8 m/s, from a height of 0.5 meters above the ground. 2.4 seconds after the blue ball is thrown, a red ball is thrown down with an initial speed of 7.9 m/s from a height of 22.5 …
  4. physics

    A red ball is thrown down with an initial speed of 1.2 m/s from a height of 25.0 meters above the ground. Then, 0.6 seconds after the red ball is thrown, a blue ball is thrown upward with an initial speed of 22.9 m/s, from a height …
  5. Physics

    A red ball is thrown down with an initial speed of 1.3 m/s from a height of 28.0 meters above the ground. Then, 0.6 seconds after the red ball is thrown, a blue ball is thrown upward with an initial speed of 24.7 m/s, from a height …
  6. math

    An object that is falling or vertically projected into the air has it height, in feet, above the ground given by the formula below, where s is the height in feet, Vo is the original velocity of the object, in feet per second, t is …
  7. Pre-Calc

    ball thrown vertically upward with an initial velocity of 80 ft per second. The distance s(in ft) of the ball from the ground after t seconds is s=80t-16t^2. a. draw the illustration. b. for what time interval is ball more than 96 …
  8. College Algebra

    Flight of a Ball If a ball is thrown upward at 96 feet per second from the top of a building that is 100 feet high, the height of the ball can be modeled by S(t)=100 + 96t -16t^2 feet, where t is the number of seconds after the ball …
  9. Algebra

    The equation h = -16t^2 + 32t + 9 gives the height of a ball, h, in feet above the ground, at t seconds after the ball is thrown upward. How many seconds after the ball is thrown will it reach its maximum height?
  10. Algebra

    The equation h= -16t^2 + 32t + 9 gives the height of a ball, h, in feet above the ground,at t seconds after the ball is thrown upward.How many seconds after the ball is thrown will it reach its maximum height?

More Similar Questions