Football kick projectile problem

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Homework Help Overview

The problem involves a place kicker who must kick a football from a distance of 35 meters to clear a crossbar that is 3.05 meters high. The ball is kicked at a speed of 26 m/s and an angle of 55 degrees to the horizontal. Participants are exploring how to determine whether the ball clears the crossbar or falls short.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss calculating the time of flight using vertical motion equations and question the validity of their time calculations. There are attempts to clarify the relationship between the ball's maximum height and its trajectory at the point of interest.

Discussion Status

The discussion is ongoing, with participants providing calculations and questioning the relevance of their findings to the specific problem. Some guidance has been offered regarding focusing on the ball's trajectory at the goal post rather than the total time of flight.

Contextual Notes

Participants are grappling with the specifics of projectile motion and the implications of their calculations, indicating a need for clarity on the problem's requirements. There is a recognition that the original poster's approach may not align with the problem's focus.

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a place kicker must kick a football from a point 35m from the goal, and the ball must clear the crossbar, which is 3.05m high. When kicked, the ball leaves the ground with a speed of 26m/s at an angle of 55 degrees to the horizontal. By how much does the ball clear or fall short of clearing the crossbar?

i found time by using Vy=Vyo-gt which is 4.826s.
what do you do next? Can you use range?
 
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Please show us your work. Over 4 seconds seems like a long time to travel 35m.
 
projectile

vy=vyo-gt. vy=0 cause is at the highest point or is it vy?
then i divided vosinangle/9.8=21.298/9.8=2.17326s

total time is 2(21.298)/9.8=4.34653s
 
nrc_8706 said:
vy=vyo-gt. vy=0 cause is at the highest point or is it vy?
then i divided vosinangle/9.8=21.298/9.8=2.17326s
Please explain this last step.
total time is 2(21.298)/9.8=4.34653s

What are you looking for?
 
nrc_8706 said:
vy=vyo-gt. vy=0 cause is at the highest point or is it vy?
then i divided vosinangle/9.8=21.298/9.8=2.17326s

total time is 2(21.298)/9.8=4.34653s

You've solved for the time it takes the football to reach it's maximum height and the time it takes until the ball strikes the ground. Your numbers look correct, but they won't help you solve the problem.

You're not interested in how far or how high the ball travels. You're interested in a certain point in the ball's trajectory. Try setting up all 4 equations (x,y,vx,vy) for that point and see if that helps.
 
Can you figure out how to answer these questions.


How long does it take the ball to cover the distance to the goal post? What information do you have that could get you this?


How high is the ball at that time?

You are computing how long it takes to reach the peak of motion and how long it takes to return to the ground, but those are not questions asked by the problem. ( just noticed grogs post, I am repeating what he had to say... sorry.
 

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