Michael Sturtevant

period 6
# Lab#10: Centripetal Force

__Objective__:

### After completing this experiment, you should be able to verify the relationship
between centripetal force, mass, and velocity in a whirling object.

__Theory__:

**Materials**

rubber stoppers

washers

string

glass tube

timer

graph paper

Meter Stick

Pencil

Paper

Calculator

__Procedure__:

### First find a flat clear place. Then cut a piece of string about 1.5 meters long and
fasten 1 end to a rubber stopper, slip the string into the glass tube, and attach a paper clip
at the appropriate length for the trial.

## Trials 1-4

### Adjust the cord to .75 meters, and put a 100g weight on the string for the 1st trial,
then whirl the stopper by moving the tube in a circular motion. When the motion becomes
steady enough that the paper clip stops moving up and down, time how long it takes to
complete 20 revolutions, and fill in your data chart. repeat the above steps using 200g for
the second trial, 300g for the 3rd trial, and 400g for the 4th trial.

## Trials 5-8

### Use the same steps as trials 1-4, but set the weight to 100g, and vary the length of
the string from .5 meters to 1 meter. Record your data.

## Trials 9-12

### Use the same steps as the above trials, but set the weight to 200g, set the string
length to 1 meter, and vary the weight of the rubber stoppers. Record this data and do
your calculations.

__Data__:

###
### Trial | ### Hanging mass (kg) | ### Mass
of Stopper (kg) | ### Total Time (s) | ### Radius (m) |

### 1 |
### .10 |
### .0223 |
### 12.11 |
### .831 |

### 2 |
### .20 |
### .0223 |
### 9.61 |
### .831 |

### 3 |
### .30 |
### .0223 |
### 6.95 |
### .831 |

### 4 |
### .40 |
### .0223 |
### 6.73 |
### .831 |

### 5 |
### .10 |
### .0223 |
### 8.44 |
### .50 |

### 6 |
### .10 |
### .0223 |
### 11.45 |
### 55 |

### 7 |
### .10 |
### .0223 |
### 12.82 |
### .60 |

### 8 |
### .10 |
### .0223 |
### 14.62 |
### .65 |

### 9 |
### .20 |
### .0215 |
### 14.29 |
### .95 |

### 10 |
### .20 |
### .0150 |
### 11.77 |
### .95 |

### 11 |
### .20 |
### .0115 |
### 10.38 |
### .95 |

### 12 |
### .20 |
### .0365 |
### 15.47 |
### .95 |

__Calculations__:

### Trial | ### Centripetal Force (N) | ### Period (s) | ### Circumference (m) | ### Velocity (m/s) |

### 1 |
### .98 |
### .61 |
### 5.2 |
### 8.5 |

### 2 |
### 1.96 |
### .48 |
### 5.2 |
### 11 |

### 3 |
### 2.94 |
### ..35 |
### 5.2 |
### 15 |

### 4 |
### 3.92 |
### .33 |
### 5.2 |
### 16 |

### 5 |
### .98 |
### .42 |
### 3.1 |
### 7.4 |

### 6 |
### .98 |
### .57 |
### 3.5 |
### 6.1 |

### 7 |
### .98 |
### .64 |
### 3.8 |
### 5.9 |

### 8 |
### .98 |
### .73 |
### 4.1 |
### 5.6 |

### 9 |
### .98 |
### .71 |
### 6.0 |
### 8.5 |

### 10 |
### .98 |
### .59 |
### 6.0 |
### 11 |

### 11 |
### .98 |
### .52 |
### 6.0 |
### 12 |

### 12 |
### .98 |
### .77 |
### 6.0 |
### 7.8 |

### Calculations and Graphs are on the last pages.

__Results__:

### In this lab we found that:

Centripetal force is related directly to velocity squared and mass, and is related inversely
to radius.

*On the basis of the first graph, what is the relationship between the velocity of
a whirling object and the centripetal force exerted on it?*

As the centripetal force increases, so does the velocity.

*What is the relationship between the radius of the revolution and the velocity
of the whirling object?*

As the radius increases, the velocity decreases.

*What is the relationship between the mass and the velocity of a whirling
object?*

As the mass increases, the velocity decreases.

*How would the shapes of the first 2 graphs change if the squares of the
velocities were used?*

The lines would become straight.

__Conclusion__:

### I think this lab was a success, because our graphs were shaped correctly and we
could easily answer the questions using the graphs. It also demonstrated the relationship of
centripetal force to mass, velocity, and radius.