calculus

a parachutist falling at the rate of 15 ft./sec. drops a stone. if he was 904 ft. above the ground when the stone was dropped, how long would it take the stone to reach the ground?

  1. 👍
  2. 👎
  3. 👁
  1. assuming a = -32
    and seeing that the initial velocity was -15 from a height of 904, I know

    s = -16r^2 - 15t + 904
    we want s = 0

    16t^2 + 15t - 904 = 0
    won't waste time trying to factor it ...
    t = (-15 ± √58081)/32
    = (-15 ± 241)/32 ----- ahh, it does factor
    = 226/32 or some silly negative
    = 113/16 seconds or appr 7.1 seconds

    btw, it would have been factored as
    (16t - 113)(t + 8) = 0

    1. 👍
    2. 👎
  2. Thank you. You’re so helpful.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Related Rates

    Sand is falling into a conical pile at the rate of 10 m3/sec such that the height of the pile is always half the diameter of the base of the pile. Find the rate at which the height of the pile is changing when the pile is 5 m.

  2. Math

    Starting from 130 feet away, a person on a bicycle rides towards a checkpoint and then passes it. The rider is traveling as a constant rate of 25 feet per second. The distance between the bicycle and the checkpoint is given by the

  3. algebra. help!

    Start from 110 feet away, a person on a bicycle rides towards a checkpoint and then passes it. The rider is travelling at a constant rate of 30 feet per second. The distance between the bicycle and the checkpoint is given by the

  4. physics

    Jack drops a stone from rest off of the top of a bridge that is 24.4 m above the ground. After the stone falls 6.6 m, Jill throws a second stone straight down. Both rocks hit the water at the exact same time. What was the initial

  1. Calculus

    The base of a triangle is decreasing at the rate of 1 ft/sec, while the height is increasing at the rate of 2 ft/sec. At what rate is the area of the triangle changing when the base is 10 ft and the height is 70 ft? a) -25

  2. calculus

    The length of a rectangle is decreasing at the rate of 2 cm/sec, while the width w is increasing at the rate of 3 cm/sec. At what rate are the lengths of the diagonals changing at the instant that l=15 cm and w= 8 cm? Are the

  3. calculus

    The Voltage v , Current I and Resistance R are related by the equation V=IR. Suppose that V is increasing at a rate of 2 volt/sec, while I is decreasing of the rate of 1/5 (amp/sec ). Let t denote time in seconds. Find the rate at

  4. Physics

    A woman on a bridge 75.0m high sees a raft floating at a constant speed on the river below. She drops a stone from rest in an attempt to hit the raft. The stone is released when the raft has 7.00m more to travel before passing

  1. science

    Question: what do you think will happen to the rate of reaction if the concentration of enzyme is increased to five drops?Predict what thte rate would be for 5 drops. Answer:Roughly, the rate doubles when the concentration of

  2. physics

    A spelunker (cave explorer) drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 3.24 s after the stone is dropped. How deep is the hole?

  3. Maaaath

    a stone thrown upward from the top of a 320-foot cliff at 128 ft/sec eventually falls to the beach below? how long does the stone take to reach its highest point?

  4. physics

    galileo drops a stone from the tower of pisa which is 45m high. at what speed does the stone hit the ground

You can view more similar questions or ask a new question.