Projectile motion

  • Thread starter kool_guy
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hello,
can someone please help me with this question

A football kicker is attempting to kick a field goal. He is 40 metres away form the goal posts, but must kick the ball so that it follows a trajectory that makes teh ball hit the ground (end zone) at a point of 50 metres away.
(a) If the player can achieve a maximum contact speed of 20 m/sat an angle of 45 degrees, will he make the field goal?
 

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Originally posted by kool_guy
hello,
can someone please help me with this question

A football kicker is attempting to kick a field goal. He is 40 metres away form the goal posts, but must kick the ball so that it follows a trajectory that makes teh ball hit the ground (end zone) at a point of 50 metres away.
(a) If the player can achieve a maximum contact speed of 20 m/sat an angle of 45 degrees, will he make the field goal?
The answer that I calculate was no. First, to calculate the time it takes to go up and down. Assuming the ball goes up from x=0, v_o in the y direction will be 20sin45. We know that v_o going up will be the velocity going down when it comes down and crosses the same height so v_o+at=v 20sin45-9.8t=-20sin45 t=-40sin(45)/.9.8 t=2.886 or so
From this, you simply do d=vt d=2.886*20cos45 and see that the answer is only 40.816, which is not long enough.
 

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