By how much does the ball clear or fall short of clearing the crossbar??

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1 Answer
Feb 28, 2018

Choosing the x coordinate of the point of the kick to be #-36" m"# so that the goal post is at #0" m"#, the functions of x and y with respect to time are:

#x(t)= (22" m/s")cos(47^@)t-36" m"" [1]"#

#y(t)= (-4.9" m/s"^2)t^2+ (22" m/s")sin(47^@)t" [2]"#

It is easy to solve equation [1] for t because, we have made the goal post at #x(t) = 0#:

#0= (22" m/s")cos(47^@)t-36" m"#

#t = (36" m")/((22" m/s")cos(47^@))#

#t ~~ 2.399" s"#

Substitute this value into equation [2]:

#y(2.399" s")= (-4.9" m/s"^2)(2.399" s")^2+ (22" m/s")sin(47^@)(2.399" s")#

#y(2.399" s") ~~ 10.39" m"#

Subtract #3.05" m"# to find the distance above the crossbar:

#d = 10.39" m" - 3.05" m"#

#d = 7.34" m"# above the crossbar.