Finding time in circular motion

In summary, the conversation discusses finding the time it takes for the blades of a food blender to make one revolution at a speed of 15 m/s and a radius of 0.052m. The equation T = 2*pi*r/velocity is suggested, but after some discussion it is determined that the correct equation is V^2/r = 4*pi^2*r/T^2. The resulting answer of 0.02 seconds is deemed incorrect and it is concluded that the original answer provided by the teacher or textbook must be wrong.
  • #1
tyro008
20
0

Homework Statement


The tips of the blades in a food blender are moving with a speed of 15 m/s in a circle that has a radius of 0.052m. How much time does it take for the blades to make on revolution?


Homework Equations


T=(2XpiXr)/T
T: period of time it takes to complete one cycle

The Attempt at a Solution


I tried using the equation under "relevant equations" and got 0.02seconds as an answer. This is wrong but I don't know what other equation to use..
 
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  • #2
Your equation is all wrong. Its T = 2*pi*r / velocity
 
  • #3
oh whoops. but.. i tried that and it still didn't work..
is there another equation that i should use instead?
i feel that my T represents time, but not the one I'm looking for
 
  • #4
Lets break it down. r = 0.052 meters. The circumference is 2 pi 0.052 which is 0.104 pi meters. It rotates at velocity 15 meters every second. So this means that it does 15/0.104 pi revolutions every second. Then just inverse that quantity to find how many seconds is one revolution
 
  • #5
i keep getting 0.02 seconds, but this isn't the right answer.
is this what you got, too?
 
  • #6
V^2/r= 4 pi^2 r/T^2

solve for T

EDIT: Forgot square T
 
Last edited:
  • #7
tyro008 said:
i keep getting 0.02 seconds, but this isn't the right answer.
is this what you got, too?

If there is another answer other than 0.02 seconds then that answer has to be wrong. Only thing else I can think of is if you got 15 m/s wrong and it was supposed to be 15 radians per second.
 
  • #8
Epsillon said:
V^2/r= 4 pi^2 r/T

solve for T

Epsillon what is this equation?? this basically says v =[tex]\frac{2\pi}{ \sqrt{T}}[/tex]
 
  • #9
Oh sorry I forgot to square the T (silly mistake)

its 4pi^2r/T^2
 
  • #10
Epsillon said:
Oh sorry I forgot to square the T (silly mistake)

its 4pi^2r/T^2

Ok it still gives v = [tex]\frac{2 \pi}{T}[/tex] which gives him the "wrong" answer. Obviously which ever book or person giving the answer is wrong.
 
  • #11
haha, thanks anyways you guys.
you know, i think you guys are right. i'll talk to my teacher about changing the answer :)
 

1. What is circular motion?

Circular motion is a type of motion in which an object moves in a circular path around a central point or axis. This type of motion is characterized by a constant speed and a continuously changing direction.

2. How do you calculate the time in circular motion?

The time in circular motion can be calculated using the formula T = 2πr/v, where T is the time in seconds, π is the value of pi, r is the radius of the circular path, and v is the speed of the object in meters per second.

3. Can the time in circular motion be negative?

No, the time in circular motion cannot be negative as it is a measure of the duration of the circular motion and cannot have a negative value.

4. How does the radius affect the time in circular motion?

The radius of the circular path has a direct impact on the time in circular motion. A larger radius will result in a longer time, while a smaller radius will result in a shorter time. This is because the larger the radius, the longer the distance the object has to travel in one circular motion.

5. Is the time in circular motion affected by the speed of the object?

Yes, the time in circular motion is affected by the speed of the object. A higher speed will result in a shorter time, while a lower speed will result in a longer time. This is because a faster moving object will cover a larger distance in the same amount of time compared to a slower moving object in circular motion.

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