Projectile Motion of a Football Problem

Click For Summary
A football is kicked towards a goal post 3.2 meters high and 30 meters away with an initial velocity of 18 meters/sec at a 50-degree angle. The horizontal and vertical components of the velocity were calculated as 11 meters/sec and 13.79 meters/sec, respectively. The time taken for the ball to reach the goal post was determined to be 2.59 seconds. To find the height of the ball at that moment, the vertical motion equations should be applied using the initial vertical velocity, time, and acceleration due to gravity. The discussion emphasizes using the correct kinematic equations to solve for the ball's height at the goal post.
Esau Garcia
Messages
1
Reaction score
0

Homework Statement


A football is kicked from the ground toward a 3.2 meter tall goal post 30 meters away. The ball leaves the ground with a velocity of 18 meters/sec at an angle of 50 degrees from the ground. How high off of the ground is the ball when it reaches the goal post? Does the kicker make the field goal? How high above or below the bar is the ball when it arrives at the goal post?

Homework Equations

The Attempt at a Solution


This is my first thread because I'm new so bare with me. I started the problem by drawing a diagram with a vector of 18 meters/sec, the horizontal component and the vertical component. I solved for each component by using basic trig functions. The results are Vy=13.79 meters/sec and Vx=11 meters/sec. From there I used the total displacement of 30 meters divided by the vertical component of 11 meters/sec to get a time of 2.59 seconds. This time would be the moment in which the ball reaches the goalpost (Is that correct?) But I'm just having difficulty answering the questions. Thanks for the help in advance.
 
Physics news on Phys.org
You've got the time at which the ball will be over head the goal post. Now just think about the motion of the ball along the vertical axis and determine how high off the ground it is. You know the inital velocity, time and acceleration.
 
Esau Garcia said:

Homework Equations

Does "SUVAT" ring a bell?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
Replies
23
Views
4K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 2 ·
Replies
2
Views
18K