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document.write( "Joe Nedney of the San Francisco 49ers kicked a field goal with an initial velocity of 20m/s at an angle of 60∘.
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document.write( "a. How long is the ball in the air? Hint: you may assume that the ball lands at the same
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document.write( "height as it starts at.
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document.write( "b. What is the distance traveled by the ball before it hits the ground?
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document.write( "c. What is its maximum height?
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document.write( "(a) Vertical component of the initial velocity is 20*sin(60°) = 
= 17.32 ft/s.\r\n" );
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document.write( " Therefore, the equation for the verical coordinate h(t) is\r\n" );
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document.write( " h(t) = -16t^2 + 17.32t\r\n" );
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document.write( " The equation to find the time of the flight is h(t) = 0, or\r\n" );
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document.write( " -16t^2 + 17.32t = 0, or\r\n" );
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document.write( " t*(16t - 17.32) = 0\r\n" );
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document.write( " We are interested in positive root, ONLY, and this root is\r\n" );
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document.write( " t = 
= 1.0825 seconds. ANSWEER\r\n" );
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document.write( "(b) The horizontal component of the speed is 20*cos(60°) = 
= 10 ft/s and is considered as a constant during the flight.\r\n" );
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document.write( " Moving with the horizontal speed of 10 ft/s during 1.0825 seconds, the ball will get the ground at the distance of \r\n" );
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document.write( " 1.0825*10 = 10.825 feet horizontally from starting position. ANSWER\r\n" );
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document.write( "(c) To find maximum height, notice that the time moving up is HALF of the total flight time, i.e., 
= 0.54125 seconds.\r\n" );
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document.write( " To find 
, calculate the function h(t) at t = 0.54125: \r\n" );
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document.write( " = -16*0.54125 + 17.32*0.54125 = 4.687 ft. ANSWER\r\n" );
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document.write( "Solved. // All questions are answered.\r
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