Centripetal force + uncertainty

In summary, to find the force on a mass using the centripetal force equation, you must first calculate the percentage uncertainties for each of the given variables (mass, velocity, and radius). Then, add up these percentages and use this final percentage as the uncertainty for the calculated force value in Newtons.
  • #1
Wa1337
33
0

Homework Statement


The centripetal force is given by F= (mv2) / r. If the mass is measured to be 2.8 +/- 0.1 kg, the velocity is 14 +/- 2 ms^-1, and the radius 8.0 +/- 0.2 m, find the force on the mass, including the uncertainty.


Homework Equations


F= (mv2) / r


The Attempt at a Solution


0.1/2.8 = .04
2/14 = .14
.2/8.0 = .025

add all up and i got .205

I did the equation and got 69 (2 sig figs) and finally got F = 69 +/- .21

Is that the proper uncertainty answer? If not please help.
 
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  • #3
edit: nvm

final answer then: F = 270 +/- .21 ? (2 sig figs both)
 
Last edited:
  • #4
Wa1337 said:
edit: nvm

final answer then: F = 270 +/- .21 ? (2 sig figs both)

I did not say the force was wrong but you changed it; moreover, you still don't have the uncertainty right as I understand it.

I guess I'm not helping.
 
  • #5
I'm sorry I kind of don't get it cause I'm really new to this stuff but my final answer without changing the force is:

F = 69 +/- 14

is that better? thanks
 
  • #6
Wa1337 said:
I'm sorry I kind of don't get it cause I'm really new to this stuff but my final answer without changing the force is:

F = 69 +/- 14

is that better? thanks

You were closer in your original post.
 
  • #7
Wa1337 said:

Homework Statement



The Attempt at a Solution


0.1/2.8 = .04
2/14 = .14
.2/8.0 = .025

add all up and i got .205

I did the equation and got 69 (2 sig figs) and finally got F = 69 +/- .21

Is that the proper uncertainty answer? If not please help.

Why is no one helping with this? I'm about to give him the answer as I think it is--it's really not something I do day-to-day but IAW to site I posted previously.

We are surpassing Winston Chruchill adage here "The Americans and the British are a single people divided only by a common language."
 
  • #8
Well he has to get the percentage uncertainties for each of the values.

So for example, for velocity it would 2/14*100 = 14.28% (quite a large uncertainty there)

Since it's squared, the uncertainty would be double: 28.57%

Do this for each of the variables, and add up the percentages. Then your final percentage of the calculated value for force should be your uncertainty in Newtons.
 

1. What is centripetal force?

Centripetal force is the force that acts on an object moving in a circular path, directed towards the center of the circle. It is responsible for keeping the object moving in a curved path rather than a straight line.

2. How is centripetal force related to uncertainty?

The uncertainty in centripetal force refers to the uncertainty in the measurements of the factors that affect it, such as the radius, mass, and speed of the object. This uncertainty can affect the accuracy of the calculated value of centripetal force.

3. What is the equation for calculating centripetal force?

The equation for centripetal force is F = (mv^2)/r, where F is the force, m is the mass of the object, v is the velocity, and r is the radius of the circular path.

4. How can uncertainty in centripetal force be reduced?

The uncertainty in centripetal force can be reduced by increasing the precision of the measurements of the factors that affect it. This can be achieved by using more accurate instruments and taking multiple measurements to calculate an average value.

5. What are the practical applications of understanding centripetal force and uncertainty?

Understanding centripetal force and uncertainty is important in various fields such as engineering, astronomy, and physics. It is used in the design of amusement park rides, satellite orbits, and the study of planetary motion. It also helps in predicting the trajectory of objects in motion and ensuring the safety and stability of structures.

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