College Physics

Two children are playing on a 178.2 m ­tall bridge. One child drops a rock (initial velocity zero) at t = 0 . The other waits 2.7 s and then throws a rock downward with an initial speed v0. If the two rocks hit the ground at the same time, what is v0 ?

for the first rock i used:
t(ground)=square root((2yo)/g)
... then I subtracted 2.7s from that number

I think you use Vo=(y-0)+.5gt^2/t
...I am not getting the correct answer. Any advice?

  1. 👍 0
  2. 👎 0
  3. 👁 246
  1. I agree that the dropped rock takes sqrt(2Yo/g) = 6.03 s to teach the ground. The thrown rock must take 6.03 - 2.7 = 3.33 s from the timne it is thrown.

    178.2 = Vo*t - (g/2)t^2

    Solve for Vo.

    Vo = (178.2 + 4.9 t^2)/t

    With parentheses in the right place, and t = 3.33 s, you should get the right answer.

    1. 👍 0
    2. 👎 0
  2. does my answer need to be negative due to the rocks falling?

    1. 👍 0
    2. 👎 0
  3. -37.19 m/s

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    A rock dropped from a bridge takes 3.21 seconds to hit the water. How high is the bridge in meters? I need to find Vsub0 to be able to calculate h....but how do I get Vsub0???

  2. Physics

    A student drops a rock from a bridge to the water 10.1 m below. The acceleration of gravity is 9.8 m/s^2. With what speed does the rock strike the water? Answer in units of m/s.

  3. 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

  4. Probability

    We are given the following statistics about the number of children in the families of a small village. There are 100 families: 10 families have no children, 40 families have 1 child each, 30 families have 2 children each, 10

  1. Physics

    A rock is thrown vertically with a velocity of 21 m/s from the edge of a bridge 41 m above the river. How long does the rock stay in the air? V = 21 m/s d = 41 m a = -9.80 m/s^2 t = ?

  2. Physics

    A rock is dropped from a high bridge. At the end of 3sec of free fall. The speed of rock is, in centimeters per second

  3. Physics

    A rock is dropped from a bridge to the water below. It takes 2.40 s for the rock to hit the water. Find the speed (in m/s) of the rock as it hits the water. How high (in metres) is the bridge above the water?

  4. PRECALC HELP!!

    Two children are playing on the seesaw. THe lighter child is 9 feet from the fulcrum, and the heavier child is 6 feet from the fulcrum. As the lighter child goes from the ground to the highest point, she travels through an angle

  1. Physics

    Two children are playing on two trampolines. The first child can bounce 1.6 times higher than the second child. The initial speed up of the second child is 5.2 m/s. (a) Find the maximum height the second child reaches. (b) What is

  2. math

    There are 10 children (aged 1 to 10 years) who have equal amounts of money. In the first transaction the eldest child gives one rupee to every child younger to him. In the second transaction, the second eldest child gives one

  3. Physics

    You throw a small rock straight up from the edge of a highway bridge that crosses a river. The rock passes you on its way down, 7.00 s after it was thrown. What is the speed of the rock just before it reaches the water 29.0 m

  4. Physics

    A student drops a rock from a bridge to the water 12.0 meters below. With what speed does the rock hit the water?

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