How Fast Did Nicole Throw the Ball?

[zellster87]

Homework Statement

This problem has really been bugging me, and i can't seem to figure it out. Heres the question:

Nicole throws a ball straight up. Chad watches the ball from a window 5.90 m above the point where Nicole released it. The ball passes Chad on the way up, and it has a speed of 15.0 m/s as it passes him on the way back down.

How fast did nicole throw the ball?

I don't understand how the guy in the window at 4.9m meters helps me at all. Any help will be greatly apprectiated. Thanks.

Homework Equations

V final = V initial + a(delta t)

The Attempt at a Solution

 

[mgb_phys]

See https://www.physicsforums.com/showthread.php?t=209642

 

[Moetasim]

Hi there,

I can definitely help you with this kinematics problem. First, let's start by understanding the given information. Nicole throws a ball straight up, meaning the initial velocity is in the upward direction. The ball then passes Chad on its way up and back down, meaning that the ball's trajectory is parabolic.

Now, let's look at the information about Chad. We know that he is watching the ball from a window that is 5.90 meters above the point where Nicole released the ball. This information is important because it tells us that the ball's maximum height will be 5.90 meters above the point of release.

Next, we are given the speed of the ball as it passes Chad on its way back down. This speed is the final velocity (V final) of the ball before it hits the ground. We also know that the initial velocity (V initial) of the ball was in the upward direction, and the acceleration (a) due to gravity is always directed downward.

Using the equation V final = V initial + a(delta t), we can solve for the initial velocity of the ball. We know that the ball's initial velocity is in the upward direction, so we can rewrite this equation as V final = V initial + (-9.8 m/s^2)(delta t). We can also use the fact that the ball's maximum height is 5.90 meters to find the time (delta t) it takes the ball to reach that height.

Once we have the time, we can plug it back into the equation and solve for the initial velocity. This will give us the speed at which Nicole threw the ball.

I hope this helps! Let me know if you have any further questions or need clarification. Good luck!