What is the correct way to find the speed of the bucket in circular motion?

AI Thread Summary
To find the speed of a bucket in circular motion, the correct approach involves understanding the relationship between centripetal acceleration and speed. The tension in the rope at the lowest point is given as 25.0 N, with the mass of the bucket being 1.80 kg. The initial calculations mistakenly focused on centripetal acceleration instead of speed. The correct formula relates acceleration to speed squared divided by radius, but the discussion highlights confusion regarding the use of time in the calculations. Ultimately, the participants emphasize the need to verify algebraic steps to arrive at the correct speed.
RedBurns
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bucket of mass 1.80 kg is whirled in a vertical circle of radius 1.10 m. At the lowest point of its motion the tension in the rope supporting the bucket is 25.0 N.
Find the speed of the bucket.

f(t)-mg=mA

25-17.64=1.8 A
7.36 = 1. 8 A
A= 4.08

I'm told the answer above is incorrect, and someone point out my mistake?
 
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RedBurns said:
bucket of mass 1.80 kg is whirled in a vertical circle of radius 1.10 m. At the lowest point of its motion the tension in the rope supporting the bucket is 25.0 N.
Find the speed of the bucket.

f(t)-mg=mA

25-17.64=1.8 A
7.36 = 1. 8 A
A= 4.08

I'm told the answer above is incorrect, and someone point out my mistake?

They are asking for the speed . You found the centripetal *acceleration*. You know how the two are related in circular motion?
 
acceleration is velocity squared over time

Speed would be 2 pi radius over time

4.08= v^2/1.10
4.08/1.1 = 3.71
Square root of 3.71 = 1.93

Would 1.93 then be the speed?
 
RedBurns said:
acceleration is velocity squared over time
no! (over the radius! Not the time!)

Speed would be 2 pi radius over time
I don't see how this help syou since you don't have the time...But it's true, if by "time" you mean the time for one rotation, the period.

4.08= v^2/1.10
4.08/1.1 = 3.71
Square root of 3.71 = 1.93

Would 1.93 then be the speed?

Check you algebra!
 
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