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Homework Statement
A 60 g ball is tied to the end of a 50-cm-long string and swung in a vertical circle. The center of the circle, as shown in Figure, is 150 cm above the floor. The ball is swung at the minimum speed necessary to make it over the top without the string going slack.
If the string is released at the instant the ball is at the top of the loop, where does the ball hit the ground?
http://session.masteringphysics.com/problemAsset/1000600/5/knight_Figure_07_62.jpg
Homework Equations
Critical velocity = [tex]V{c}[/tex] = [tex]\sqrt{r*g}[/tex]
[tex]\Delta[/tex]d=V{i}*t + (1/2)(a)(t^2)
The Attempt at a Solution
I attempted this problem as a projectile motion problem, and divided the calculations into two parts: Horizontal and Verticle
Verticle Part
So I used this equation: [tex]\Delta[/tex]d=V{i}*t + (1/2)(a)(t^2) and I know the verticle initial is 0 so I can eliminate V{i}*t of the equation and get: [tex]\Delta[/tex]d=(1/2)(a)(t^2)
2 = (1/2)*(9.8)*(t^2)
2 = 4.9*(t^2)
t^2 = 2 / 49
t = 0.64 seconds
Horizontal Part
The horizontal parts only has 3 variables: V, d, and t (which I know from the verticle part). and V = V{c} = [tex]\sqrt{r*g}[/tex] = 0.59 m/s.
and d = v*t = 0.59*0.64 = 0.3776 m
This doesn't look right. I was wondering if someone can point me in the right direction. Any help is greatly appreciated. Thanks.
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