In 1998, Jason Elam kicked a record fild goal. The football started on the groun

Question

In 1998, Jason Elam kicked a record fild goal. The football started on the ground 62.0 yards from the base of the goal posts and just barely cleared the 10-ft-high bar. The initial trajectory of the football was 38.0 above the horizontal.

1)What was its initial speed? (Neglect any effects due to air resistance.) (Express your answer to two significant figures.)

2)How long after the ball was struck did it pass through the goal posts? (Neglect any effects due to air resistance.) (Express your answer to two significant figures.)

Explanation / Answer

1] let the initial speed be v and time taken be t.
t = d/[vcos 38 degree] also 62 yards = 56.693 m

= 56.693/[ 0.788v] = 71.945/v

height h = v sin 38 degree t - 0.5*9.8*t^2

10*0.3048 = v* sin 38 degree * 71.945/v - 4.9t^2

3.048 = 44.29 - 4.9t^2

t = sqrt ((44.29-3.048)/4.9)

= 2.9 s

v = 71.945/t = 71.945/2.9

= 25 m/s answer

b] t = 2.9 s as found above

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