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 September 20th, 2013, 09:21 AM #1 Member   Joined: Aug 2013 Posts: 69 Thanks: 0 Circular Acceleration Hi, question 1:" a steel ball that is accelerated on a circular track of radius 72cm reaches a speed of 4.0m/s over three circuits, starting from rest. How long after the ball starts to move does its radial accel = tangential accel. How many turns does that ball take for that to happen? Assume contant tang accel. 2.An object moves in a cirtial circle of radius 4m, the speed of the object is 12m/s when the object is 30deg above the lowest point along the circle, and 8m/s when the object is at the top of the circle. the tan accel is uniform. what is the total accel of the objet when its speed is 8m/s I have ways of doing this myself. but im not getting the correct answers all the way through, I think my intuition about accell are off. ..f I can accurately figure out a tan i can do some wokr. Zen~ September 25th, 2013, 09:35 PM   #2
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Re: Circular Acceleration

Hi Zen,

Here is how I worked the problems. I hope that my answers are correct (I have my doubts about problem #2 though).

Units are: time, s; distance, m; speed, m/s; acceleration, m/s^2

Problem #1

First find the acceleration a:

(the 3 is 3 revolutions)

substituting and solving for a we get

Quote:
 How long after the ball starts to move does its radial accel = tangential accel.

Quote:
 How many turns does that ball take for that to happen?

Problem #2

I interpret the problem as the object decelerating as it moves through radians.

Again, let's find the tangential a

At the point of interest, the velocity is 8 and the distance traveled is

The resultant acceleration magnitude is with an angle of direction that is

away from the radius line pointing back in the direction that the object came since it is decelerating.

I hope this is close. Tags acceleration, circular 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 Mike7remblay Physics 3 February 1st, 2012 06:48 PM MasterOfDisaster Physics 4 June 14th, 2011 01:44 PM TheSame Calculus 9 May 25th, 2011 06:06 PM JosephE Algebra 2 February 13th, 2010 08:38 AM imcutenfresa Calculus 5 October 7th, 2009 02:51 PM

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