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.

https://www.angelfire.com/al/physicslab/lab10.html