April 29th, 2017, 09:47 AM  #1 
Senior Member Joined: Feb 2016 From: seattle Posts: 377 Thanks: 10  Determine the height of the Mountain....
I am doing number 2 a is the height of the moutian as easy as just the 500? Thanks

April 29th, 2017, 10:01 AM  #2 
Math Team Joined: Jul 2011 From: Texas Posts: 2,755 Thanks: 1405 
yes ... height of the mountain is h(0) = 500 meters

April 29th, 2017, 10:16 AM  #3 
Senior Member Joined: Feb 2016 From: seattle Posts: 377 Thanks: 10  
April 29th, 2017, 10:32 AM  #4 
Math Team Joined: Jul 2011 From: Texas Posts: 2,755 Thanks: 1405 
$a$ is the coefficient of the quadratic term, $a = 4.9$ $b$ is the coefficient of the linear term, $b = 196$ $c$ is the constant term, $c=500$ 
April 29th, 2017, 10:46 AM  #5  
Senior Member Joined: Feb 2016 From: seattle Posts: 377 Thanks: 10  Quote:
Okay, I think I messed up my words again... I guess I am just confused how they got the numbers? How did they know what numbers to put in for a and c? I am guessing it's because they already had the numbers? Cause now they want me to plug in numbers for a b and c I think, but by writing a new.... Assuming its height is a quadratic function of time, how long will it spend in the air? A ball is thrown into the air from 6 feet above the ground. It reaches its maximum height of 18 feet in 3 seconds So I would think c=6 18 is maybe our b and a is maybe our unknown? Last edited by skipjack; April 29th, 2017 at 11:29 PM.  
April 29th, 2017, 11:00 AM  #6  
Math Team Joined: Jul 2011 From: Texas Posts: 2,755 Thanks: 1405 
The general equation for projectile motion in one dimension is $h(t) = \dfrac{1}{2}gt^2 + v_0 \cdot t + h_0$ in English units, $g = 32 \, ft/sec^2$ in metric units, $g = 9.8 \, m/sec^2$ Quote:
$a = 16$ The $b$ value is the initial velocity of the projectile ... $b = v_0$ The $c$ value is the initial height of the projectile ... $c = h_0$ You are given $h(0) = 6 = c$ and $h(3) = 18$ ... $18 = 16(3^2) + v_0(3) + 6$ Now you can solve for $b = v_0$ and determine the equation for height as a function of time. Last edited by skipjack; April 29th, 2017 at 11:31 PM.  
April 29th, 2017, 11:11 AM  #7  
Senior Member Joined: Feb 2016 From: seattle Posts: 377 Thanks: 10  Quote:
Hmm okay, so other than from you, where would I have learned that g equals 32? and to halve it as you have? Last edited by skipjack; April 29th, 2017 at 11:32 PM.  
April 29th, 2017, 11:25 AM  #8  
Math Team Joined: Jul 2011 From: Texas Posts: 2,755 Thanks: 1405  Quote:
(a) your textbook if it has examples of these projectile motion problems (b) your instructor if he/she did example problems in class (c) yourself, if you did a web search ... Quadratics in the real world Last edited by skipjack; April 29th, 2017 at 11:33 PM.  
April 29th, 2017, 08:55 PM  #9  
Senior Member Joined: Feb 2016 From: seattle Posts: 377 Thanks: 10  Quote:
 
April 30th, 2017, 08:08 AM  #10 
Senior Member Joined: Feb 2016 From: seattle Posts: 377 Thanks: 10  going back to the original problem /application
How come I am not coming up with a Decimal ? Thanks 

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