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 August 26th, 2013, 04:15 PM #1 Senior Member   Joined: Apr 2013 From: Ramallah, Palestine Posts: 349 Thanks: 0 Height of a ball Height of a ball after t seconds is given by Find the average velocity from t = 2 to t = 2.1 How do I approach this? August 26th, 2013, 06:11 PM #2 Global Moderator   Joined: Dec 2006 Posts: 20,965 Thanks: 2214 Calculate (y(2.1) - y(2))/(2.1 - 2) = -25.6. The vertical component of the required average velocity is 25.6 height units per second, directed downwards. August 27th, 2013, 01:08 AM #3 Newbie   Joined: May 2013 Posts: 16 Thanks: 0 Re: Height of a ball Solution: Given height of the ball after t second y(t)=40t-16 t� at t=2 ,y(2)=40*2-16*(2)� y(2)=16 at t=2.1, y(2.1)=40*(2.1)-16(2.1)� y(2.1)=13.44 average velocity =[y(2.1)-y(2)]/[2.1-2] average velocity = -25.6 therefore average velocity is 25.6,-ve sign shows direction downwards August 27th, 2013, 01:57 AM #4 Math Team   Joined: Jul 2013 From: काठमाडौं, नेपाल Posts: 901 Thanks: 61 Math Focus: सामान्य गणित Re: Height of a ball average velocity = (final velocity + initial velocity)/2 is this valid only for constant acceleration ? August 27th, 2013, 01:59 AM   #5
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Re: Height of a ball

Quote:
 Originally Posted by MATHEMATICIAN average velocity = (final velocity + initial velocity)/2 is this valid only for constant acceleration ?
I think so yes. But we don't know the final nor the initial velocity. August 27th, 2013, 04:03 AM   #6
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Re: Height of a ball

Quote:
 Originally Posted by MATHEMATICIAN average velocity = (final velocity + initial velocity)/2 is this valid only for constant acceleration ?
Yes, only for constant acceleration. It might be more natural first to calculate the velocity by differentiating:

v(t) = 40 - 32t

v(2) = -24 and v(2.1) = -27.2 Tags ball, height Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post hikagi Calculus 4 January 23rd, 2018 04:04 PM mathkid Physics 16 February 22nd, 2013 03:12 AM r-soy Physics 4 June 14th, 2012 05:43 AM xinglongdada Real Analysis 3 June 7th, 2012 11:13 PM cloudtifa Advanced Statistics 0 October 18th, 2010 06:58 PM

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