document.write( "Question 139518: hello....I am stumped...hope you can help...Question: Assume Joe Ball hits a major league pop-up (straight upward) on a Johnny Bench 90mph pitch. The function that describes the ball's height (in feet/second) is: h(t) = -16t^2+132t h(t) is height, t = is seconds...How many seconds for the ball to go up and back down? How high does the ball go? I came up with answers 4.125 for ball to go up and down and 272.25 feet for how high ball goes up (correct??)...but here's the stumper: it's now asking to repeat problem using planet Mercury. How do I complete this? (FYI, Mercury is 38% of Earth)....Hope you can help and show me the correct formula and answers..Thank you \n" ); document.write( "
Algebra.Com's Answer #101713 by Earlsdon(6294)\"\" \"About 
You can put this solution on YOUR website!
Let's look at part I of the problem:
\n" ); document.write( "I)
\n" ); document.write( "a) How many seconds for the ball to go up and down?
\n" ); document.write( "In other words, how many seconds for the ball to return to the ground?
\n" ); document.write( "Starting with the given formula:
\n" ); document.write( "\"h%28t%29+=+-16t%5E2%2Bv%5B0%5Dt%2Bh%5B0%5D\" where:
\n" ); document.write( "\"v%5B0%5D+=+132\"ft/sec This is the initial upward velocity.
\n" ); document.write( "\"h%5B0%5D+=+0\" This is the initial height.
\n" ); document.write( "So we have:
\n" ); document.write( "\"h%28t%29+=+-16t%5E2%2B132t\" and you want to find the time, t, when h = 0:
\n" ); document.write( "\"0+=+-16t%5E2%2B132t\" Factor a t from the right-hand side.
\n" ); document.write( "\"0+=+t%28-16t%2B132%29\" Apply the zero product rule: If \"a%2Ab+=+0\" then either \"a+=+0\" or \"b+=+0\" or both.
\n" ); document.write( "Add 16t to both sides. So...
\n" ); document.write( "\"t+=+0\" or \"-16t%2B132+=+0\"
\n" ); document.write( "\"-16t+%2B+132+=+0\" Add 16t to both sides.
\n" ); document.write( "\"132+=+16t\" Divide both sides by 16.
\n" ); document.write( "\"t+=+8.25\"seconds.
\n" ); document.write( "The ball returns to the ground in 8.25 seconds.
\n" ); document.write( "b) How high does the ball go?
\n" ); document.write( "You'll need to find the value of t at the vertex of the parabola described by the given equation. This is given by:
\n" ); document.write( "\"t+=+-b%2F2a\" The a and b come from: \"ax%5E2%2Bbx%2Bc+=+0\" and in this case, a = -16 and b = 132.
\n" ); document.write( "\"t+=+%28-132%29%2F2%28-16%29\"
\n" ); document.write( "\"t+=+4.125\" seconds. This is the time at which the ball reaches its maximum height. Substitute this value of t into the given equation and solve for h to find the maximum height.
\n" ); document.write( "\"h%284.125%29+=+-16%284.125%29%5E2%2B132%284.125%29\"
\n" ); document.write( "\"h%284.125%29+=+-272.5%2B544.5\"
\n" ); document.write( "\"h%284.125%29+=+272.25\" feet. Which is precisely what you got.
\n" ); document.write( "II) For this problem to be solved for the planet Mercury whose gravitational force is 38% that of earth's, let's look at the original formula for the height of an object propelled upwards:
\n" ); document.write( "\"h%28t%29+-+%281%2F2%29gt%5E2%2Bv%5B0%5Dt%2Bh%5B0%5D\"
\n" ); document.write( "Here, the acceleration due to gravity is: g = 32 ft/second squared for earth.
\n" ); document.write( "For Mercury, g = 0.38(32)ft/second squared = 12.16 feet/second squared.
\n" ); document.write( "So the formula for the planet Mercury becomes:
\n" ); document.write( "\"h%28t%29+=+-%281%2F2%2912.16t%5E2%2Bv%5B0%5D%2Bh%5B0%5D\"
\n" ); document.write( "\"h%28t%29+=+-6.08t%5E2%2Bv%5B0%5Dt%2Bh%5B0%5D\" This is the formula you would use to solve the second part of the problem.
\n" ); document.write( "a)
\n" ); document.write( "\"h%28t%29+=+-6.08t%5E2%2B132t\" Set h = 0 and solve for t.
\n" ); document.write( "\"0+=+-6.08t%5E2%2B132t\" So...
\n" ); document.write( "\"t+=+0\" or...
\n" ); document.write( "\"t+=+132%2F6.08\"
\n" ); document.write( "\"t+=+21.71\" seconds. This is the time at which the ball returns to the ground on Mercury.
\n" ); document.write( "The time to reach its maximum height is:
\n" ); document.write( "\"t+=+-b%2F2a\" where: a = -6.06 and b = 132.
\n" ); document.write( "\"t+=+-%28132%2F2%28-6.08%29%29\"
\n" ); document.write( "\"t+=+10.86\"seconds. Substitute this into the formula for Mercury:
\n" ); document.write( "\"h%2810.86%29+=+-6.08%2810.86%29%5E2%2B132%2810.86%29\"
\n" ); document.write( "\"h%2810.86%29+=+-66%2B1433.52\"
\n" ); document.write( "\"h%2810.86%29+=+1367.52\"feet. This is the maximum height attained by the ball on Mercury.\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );