Finding Centripetal Force Using Lab Data

In summary, the lab involved setting up a string, two masses, and a tube. By timing how long it took for a mass to complete 10 revolutions, students were able to calculate the period (T) and change the radius to repeat the experiment. Results for 5 different radii and periods were obtained and a graph of Radius vs Period2 (T2) was made. The slope of this line was said to give the Centripetal Force, but the equation used (r = (F/4π2m)T2) suggests that the slope should be (F/4π2m) instead of just F. The force of gravity acting on the bottom mass is balanced by the centripetal force on the
  • #1
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Homework Statement



So in lab, we had this setup where we had a string, two masses, and a tube. We attached one of the masses, then put the string through the tube, and attached the other mass on the other end.

Then, by holding the tube, we were to spin a mass above our heads and time how long it took to get 10 revolutions, then divide this time by 10 to get the Period (T). We then change the radius, and repeat 4 times.

So, at the end, we have results for 5 different radii and 5 different periods. We are then told to make a graph of Radius vs Period2 (T2)

According to the lab, the slope of this line is supposed to give us the Centripetal Force.

However, according to the following equation:

Homework Equations



r = (F/4[itex]\pi[/itex]2m)T2

The Attempt at a Solution



The slope of r/T2 seems like it should be (F/4[itex]\pi[/itex]2m)... not simply F.

Also... which mass am I supposed to use in this equation?
 
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  • #2


A picture/sketch of what was being done would be helpful.
 
  • #3


If I understand, there is one mass dangling out the bottom of the tube, and another attached to the string whirling around the top of the tube. The force of gravity acting on the bottom mass is balanced by the centripetal force on the top mass. That gives you

[itex] m_1g = m_2rω^2 = m_2r(2π/T)^2[/itex]

What do you get when you solve for [itex]r/T^2[/itex] ?
 

1. What is centripetal force?

Centripetal force is a force that acts on an object moving in a circular path, directed towards the center of the circle. It is necessary to keep an object moving in a circular path with a constant speed.

2. How is centripetal force calculated?

Centripetal force can be calculated using the equation Fc = mv^2/r, where Fc is the centripetal force, m is the mass of the object, v is the velocity, and r is the radius of the circular path.

3. How can lab data be used to find centripetal force?

In a lab, centripetal force can be found by measuring the mass, velocity, and radius of an object moving in a circular path and plugging those values into the centripetal force equation.

4. What are some common sources of error when finding centripetal force using lab data?

Some common sources of error include inaccurate measurements of mass, velocity, and radius, friction or air resistance affecting the motion of the object, and human error in recording data or performing calculations.

5. How can the accuracy of the results be improved when finding centripetal force using lab data?

The accuracy of the results can be improved by taking multiple measurements and calculating the average, using precise and calibrated instruments, minimizing the effects of friction or air resistance, and double-checking all calculations and data recording.

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