Lab Template_Friction

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Mt San Antonio College *

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211

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Mechanical Engineering

Date

Apr 3, 2024

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doc

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Uploaded by jesusgonzalezjg735

Title of the Experiment: Friction Student’s name: Jesus Gonzalez Section SLN: 74465 TA’s Name: Ayush Kumar Singh Week of the experiment: 4 1

Objectives: (3 points) The objective of this lab is to apply the friction force concept to different situations in the experiment and to be able to calculate coefficients of static and kinetic friction and know the distinction between them. Experimental Data (3 points): PART 1. Static Friction 1a) Cart on the horizontal track 1b) Cart on an inclined plane 2 Trial Critical angle (Θ) 1 10.3 2 10.3 3 10.3 Mass of the cart, M = 650g or .65kg Mass of the hanger, m = 50g or 0.05kg Mass on the hanger, m w = 0.07kg Total mass of the hanger m h = 0.12kg Mass of the cart, M = .65kg

PART 2. Kinetic friction 2a) Cart on the horizontal track 2b) Cart on an Incline plane. Data Analysis (10 points): PART 1. Static Friction 1a) Cart on the horizontal track. 3 Run acceleration, a 1 -.02 +-3.26E-005 m/s 2 .12 +-.00016m/s Run acceleration, a 1 .0025 m/s 2 .32 m/s Mass of the cart, M = 250 + 320 = 570g = .57kg Mass of the hanger, m = .05kg Mass of the cart, M = .55kg

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 The experimental value of the coefficient of the static friction µ s calculated as follows: F_n=mg=.650*9.8= 6.37N T=mg= .120*1.18 = 1.18N f_s=T u_sF_n=Tu_s(6.37)=1.18 u_s=.19  The discrepancy between the experimentally determined µ s and its actual given value has been calculated to be: U_s=tan(x)=tan(10.3)=0.182 .182-.18= .002 1b) Cart on an Incline plane  The experimental value of the coefficient of static friction µ s is calculated with equation (4) as follows: u_s = tan(x) tan(10.3) u_s=.1317  Determine the discrepancy between the above-calculated value and the given one to compare them: 100%* ( | calc. value– expect. value | / expect. value). (.1317-.18)/.18 .96% PART 2. Kinetic friction 2a) Cart on the horizontal track  For run 1 the coefficient of kinetic friction μk is calculated as follows: μk = [mhg-(M+mh)a]/M*g .08776  For run 2 the coefficient of kinetic friction μk is calculated as follows: 4

=.06862  The average values of coefficient of kinetic friction μk from both runs is: Avg = (.08776+.06862) / 2 .07819  The discrepancy between the experimental and theoretical values is: μk(avg) – actual |.07819-.09| .1181 2b) Cart on an Incline plane.  For run 1 the coefficient of kinetic friction μk is calculated as follows: uk = (gsinx+a)/gcosx (9.8sin5+.025)/gcos5 Uk=0.09  For run 2 the coefficient of kinetic friction μk is calculated as follows: (9.8sin7+.032)/gcos7 Uk=0.155  The average values of coefficient of kinetic friction μk from both runs is: Ukavg = (.155+.09)/2 uk= .1225  The discrepancy between the experimental and theoretical values is: .0325 5

Res u lts (3 points) Horizontal Run 1 : -.02 m/s Run 2: .12 m/s Incline Run 1: .0025 m/s Run 2: .32 m/s Discussion and Conclusion (10 points): In this experiment we used a cart with additional massed attached to a hangar hanging to the end with a rope to make the car move along a ramp with a certain coefficient of friction in a horizontal slope and on an incline. The values of the coefficients of kinetic and static friction compare to each other because the coefficient of static friction is always greater than that of its kinetic friction, this makes sense because you need more force to get something to move from rest and when moving it is easy to allow it to keep moving, therefore the kinetic friction is much smaller. The reason for discrepancies is that theoretically it is perfectly smooth and maintains that friction all around, in the real-world surfaces are not perfectly smooth there are many things that can affect the surface such as imperfections. In conclusion we learned about using the equations to find the frictional forces and its coefficients by doing this experiment and the nature of these forces and how they relate to each other. 6

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