Physics

posted by .

A ball is thrown horizontally from a height of 16.01 m and hits the ground with a speed that is 5.0 times its initial speed. What was the initial speed?

Ok so I got a vertical final velocity of 17.714 m/s. Now I need to find the horizontal speed, correct? Which equation can I use?

  • Physics -

    What you have calculated is the vertical component of the velocity at impact (Vy), not the full speed. The full speed at impact is sqrt (Vx^2 + Vy^2) You need Vx, which is the same as the horizontal velcoity when it was thrown. Vx was the initial speed.
    sqrt (Vx^2 + Vy^2) = 5 Vx
    Vx^2 + Vy^2 = 25 Vx^2
    Vy = sqrt(24)* Vx
    Vx = 0.2041 Vy = ?

  • Physics -

    Ok...explain to me how u obatined the final velocity

  • Physics -

    The final velocity contains two perpendicular components, horizontal and vertical. Using the pythoreagan theorm,

    vf= sqrt(vhoriztal^2+ vvertical*2)
    In this case, one knows that Vf=4vhorizontal, and one knows the Vvertialfinal.

    Solve for vhorizontal.

  • Physics -

    But my number was correct, right? 17.714 m/s?

  • Physics -

    And drwls...where is 0.2041 coming from?

  • Physics -

    Your number was correct for Vy. You are asked to calculate Vx. You get it by knowing that Vx = sqrt(Vx^2 + Vy^2)

  • Physics -

    All right. So this is what my equation looks like so far. I need to solve for Vx:
    25Vx^2 = 313.786 + Vx^2

    Correct?

  • Physics -

    All right n/m, I finally got the answer. :)

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Physics

    A ball is thrown upward from the ground with an initial speed of 25 m/s; at the same instant, a ball dropped from rest from a building 15 m high. After how long will the balls be at the same height?
  2. Physics

    A stone thrown horizontally from a height of 7.8 m hits the ground at a distance of 12.0 m. Calculate the speed of the ball as it hits the ground. I was able to find the initial speed of the ball, which is 9.52 m/s. However, I'm unsure …
  3. Physics

    A ball is thrown horizontally from a height of 16.01 m and hits the ground with a speed that is 5.0 times its initial speed. What was the initial speed?
  4. Physics

    A ball is thrown horizontally from a height of 19.17 m and hits the ground with a speed that is 4.0 times its initial speed. What was the initial speed?
  5. physics

    A ball is thrown horizontally from a height of 18.18 m and hits the ground with a speed that is 4.0 times its initial speed. What was the initial speed?
  6. 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 …
  7. 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 …
  8. physics

    A ball is thrown horizontally from a height of 24.93 m and hits the ground with a speed that is 3.0 times its initial speed. What was the initial speed?
  9. physics

    A ball is thrown horizontally from a height of 24.93 m and hits the ground with a speed that is 3.0 times its initial speed. What was the initial speed?
  10. physics

    A blue ball is thrown upward with an initial speed of 24.1 m/s, from a height of 0.6 meters above the ground. 2.9 seconds after the blue ball is thrown, a red ball is thrown down with an initial speed of 8.5 m/s from a height of 31.8 …

More Similar Questions