Kinematics of a kicked football

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SUMMARY

The discussion focuses on solving a kinematics problem involving a kicked football, specifically using the equations of motion. Key equations mentioned include the horizontal position equation, x = vcos(theta)t, and the range equation, R = v^2sin(2theta)/g. Participants emphasize the necessity of incorporating the vertical position equation to determine the time when the football reaches the height of 3.05 meters. The conclusion suggests that without the vertical motion equation, solving the problem is incomplete.

PREREQUISITES
  • Understanding of kinematic equations, specifically for projectile motion.
  • Familiarity with the concepts of horizontal and vertical motion in physics.
  • Knowledge of trigonometric functions and their application in physics.
  • Basic algebra skills for manipulating equations and solving for variables.
NEXT STEPS
  • Study the vertical position equation for projectile motion, y = vi*sin(theta)t - 0.5gt^2.
  • Learn how to apply the range equation R = v^2sin(2theta)/g in practical scenarios.
  • Explore the concept of significant figures in physics calculations.
  • Practice solving kinematics problems involving projectile motion with varying angles and initial velocities.
USEFUL FOR

Students studying physics, particularly those focusing on kinematics and projectile motion, as well as educators seeking to clarify these concepts for their students.

Josh0768
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Homework Statement
Please help, I am thoroughly stumped trying to solve this kinematics question on my study guide. I’ve tried everything I know of but cannot get an answer that’s even an option.
Relevant Equations
R = v^2sin(2theta)/g
v^2 = vi^2 -2gd
x = vcos(theta)t
CE4D7DFC-357D-4EE6-8509-0FA17B8B104A.jpeg
 
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Josh0768 said:
x = vcos(theta)t
You could solve that equation for the time it takes to reach the horizontal position of the goal post.
It seems to me that you have forgotten to write down the equation for the vertical position of a ballistic object as a function of time.
 
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Josh0768 said:
I’ve tried everything I know
I assume you would like us to tell you where you are going wrong. Just a moment while I get out my crystal ball...
 
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Hello Josh.

How are you going to solve this problem without the equation for vertical position as a function of time? If you can figure out the elapsed time when the football is at the required height (3.05 m.) I think you can you then solve the rest of the problem.

AM
 
Josh0768 said:
Homework Statement: Please help, I am thoroughly stumped trying to solve this kinematics question on my study guide. I’ve tried everything I know of but cannot get an answer that’s even an option.
Homework Equations: R = v^2sin(2theta)/g
v^2 = vi^2 -2gd
x = vcos(theta)t

View attachment 249715
according to me the answer should be "G". Use equation of trajectory and put x=32.3 v=22.2 and theta=49.4 after plugging in the values you should get some "y" after that just subtract the height of the goal post.
 
If significant figures are to be taken into account, none of the answers are correct.

AM
 

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