Lab 5 Lab Report 6q715t

PHYS 1730

09/29/14

Experiment 5 Friction and the Inclined Plane

Andrew Barnes

PHYS 1730

09/29/14

Introduction: The purpose of the experiment is to be able measure the coefficient of friction between two objects through two different methods and to determine factors that have an influence on the coefficient of friction. The nature of this coefficient will be observed and explored in the experiment with the use of weights and with the use of an incline plane to help set up many different scenarios. The variables that will changed will be the mass of the block, the surface area of the block that maintains with the plane during motion, and the incline of the plane in which the block is sliding. Theory: It is predicted that the values of the coefficient of kinetic friction that will be obtained during the experiment will vary due to the differences in conditions of the block in each scenario tested. All three factors, weight of the block, surface area of the block touching the plane, and angle of inclination of the block are expected to have an influence on this value. It is predicted that the blocks with more weight, less inclination, and greater surface area will contribute to higher values of the coefficient of friction. The coefficient of friction between two objects can be derived from the following equation: , where

is the total force of friction,

is the coefficient of kinetic friction, and

is the normal force acting on the object. By simply rearranging this equation, the coefficient of friction can be calculated by:

.Another method of finding the coefficient of friction is to

use the dimensions of an inclined plane. This method is as follows:

, where

the angle of the inclined plane, b is the length of the base of the inclined plane, and h is the height of the incline at the specified angle . Figure 1 displayed below shows this concept in more detail.

is

PHYS 1730

09/29/14

Experimental Procedure: First, the weight of the wooden block used throughout the experiment will be determined. The block will then be placed on a flat wooden plane and hooked up to a string and pulley that is connected to a weighted hanger. This setup will be used to calculate the pulling force and coefficient of friction of the scenarios in Table 1, pertaining to variances in weight and surface area of the wooden block against the plane. Weights will be added to the hanger that is connected to the block until the wooden block slides across the plane at a constant velocity. The block must be moving at a constant velocity in order to measure the coefficient of kinetic friction. The same procedure will be repeated in Table 2, except with the inclined plane positioned at the different angles specified in Table 2. Finally, the wooden block will be tested once more through the use of the inclined plane and the force of gravity and friction, without the use of the weights and hanger attached to the block. The data for this will be recorded in Table 3.

PHYS 1730 Data:

09/29/14

PHYS 1730

09/29/14

Analysis/ Discussion of Results: It was observed that the coefficient of friction was unchanged by the mass and area of by the wooden block as it slid across the plane. The value of this coefficient stayed relatively constant, with an average experimental value being 0.465, obtained from Table 1. It was observed that the angle of the incline, on the other hand, had an effect on the coefficient of kinetic friction, with the

being proportional to the angle raised. Meaning the higher the

angle raised, the lower the µ value. This relationship can be shown with the data collected in Table 2, by comparing the angle

to the coefficient of friction found with this scenario. The

differences in the µ values calculated throughout the experiment were mainly due to human error. This error could have occurred on a number of measurements made during the experiment, from measures made using a measuring stick to the determination of constant velocity by the wooden block simply by eyeballing it. The use of technology to determine the measurements needed would have this data more consistent. Conclusion: The coefficient of kinetic friction was determined to be only influenced by the angle of inclination and not by mass and surface area. The results were obtained experimentally through the collection of data on many scenarios that were then compared to each other for differing values in the coefficient of kinetic friction. The results were not as expected, as the hypothesis was that all the conditions described above would make a difference in the coefficient of friction. The data collected showed that this was not true and only the angle of inclination had an apparent effect.