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Subject:
Physics
Category: Science > Physics Asked by: kenpoman42-ga List Price: $5.00 |
Posted:
17 Feb 2006 22:38 PST
Expires: 19 Mar 2006 22:38 PST Question ID: 447190 |
If I toss a ball in the air at 32 feet per second how high will it go? | |
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Subject:
Re: Physics
Answered By: richard-ga on 18 Feb 2006 05:45 PST |
Hello and thank you for your question. Click here: http://www.ncsu.edu/felder-public/kenny/images/physicist/rockthrow.gif The formula that relates velocity, uniform acceleration, and distance (s) is (v final)^2 = (v initial)^2 + 2 * a * s so in your case since the ball will have v=0 at the top of its path, 0 = 32^2 + 2 * 32 * s or 64s = 32^2 s = 16 feet There's a rule of symmetry that says this is the same as the height you would drop a ball from that would give it v=32 when it hits the ground. If you can't assume knowing the above formula, you can get the same answer in two steps: Step 1: How much time? v = at 32 = 32t t = 1 second Step 2: How far? s = 1/2 * a * t^2 s = 16 If you want to read more about this problem, take a look at http://www.ncsu.edu/felder-public/kenny/papers/physicist.html Cheers Google Answers Researcher Richard-ga |
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Subject:
Re: Physics
From: mathisfun-ga on 18 Feb 2006 00:46 PST |
Well the relationship between acceleration velocity and placement is that each is the antiderivitive of the one before it so: Acc due to gravity = -32 ft/sec^2 integrate with respect to t and velocity is -32t + c setting t to zero and knowing that original velocity was 32 ft/sec we have v(0)=0+c=32 ft/sec so c=32 and v(t) = -32t + 32 to find placement we integrate again and get -16t^2 + 32t + c setting placement at time zero we can solve for c by s(0)=0=0+0+c => s(t)=-16t^2+32t since we are concerned with placement at time 1 s(1)=-16(1)^2+32(1)= 16 Feet, so ignoring wind resistance and holding acceleration due to gravity to -32 ft/sec^2 the ball with be 16 feet higher from the place it left your hand and have a velocity of 0 feet per second with acceleration of -32 feet per second squared. I hope this is what you had in mind by "show the math" ~mathisfun |
Subject:
Re: Physics
From: mathisfun-ga on 21 Feb 2006 03:20 PST |
I would be careful with the equation of s=1/2*a*t^2 in the future, this is true for dropping a ball or transversely throwing the ball to its pinnacle, however would not work for instance if you through the ball in the air at the speed of 32 ft/sec and wanted to know where it was 1.5 seconds later. In that case calc will quickly show for given acceleration constant "a" we have a(t) = a v(t) = at + c where c is initial velocity s(t) = 1/2*a*t^2 + Vo*t + c, where in this case c is the initial placement. which leads us to: s(t) = (1/2 * a * t^2) + (Vo * t) + So where a is acceleratoin, Vo is original velocity, So is original placement and t is of course time. Example: Say you are standing 60 feet above the ground and throw a ball up at (+)32 feet per second with gravity pulling it down at (-)32ft/sec^2 and whant to know where the ball is relative to the ground after 3 seconds. s(3) = (1/2)*(-32)*(9) + 32*3 + 60 = 12 feet above the ground. |
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