Force of Friction Lab PDF

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Force of friction Lab...

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3/7/2021 PHY 133 TA: Sergey Alekseev Friction

Introduction In this lab we will be measuring the force of friction and how it changes with mass. Friction is a force that opposes the sliding of an object and there are two types of friction; static and kinetic. This lab will focus on kinetic friction which is the force that acts between moving surfaces or the force that opposes motion while an object is in motion. Once an object moves across a surface it will experience a force in the direction that opposes its own movement. Meanwhile, the magnitude of the force depends on the coefficient of friction that varies between different materials. If we know the mass and acceleration of an object, we will be able to solve for the coefficient of friction between the object and the surface. During the lab, we will be pushing an object with increasing mass over a horizontal surface to calculate the coefficient of friction and we can predict that the coefficient remains constant even as the mass changes.

Methods/ Procedure Finding mass of device 1. Turn on the iOLab device and plug the dongle into the computer 2. Attach the screw to the remote and turn the device so that the y-axis is pointing downwards. 3. Record this motion for 1 second, then lift the device using the screw. 4. Record the acceleration and the force 5. Find the mass using the equation F=mg Giving device a push 1. Replace the screw with the plate 2. Place the device wheels up and give the device a push from the plate in the y direction

3. Find the acceleration of your device after you pushed it by using analysis mode 4. Uncheck Ax and Az boxes Procedure 1. Attach a first mass mass with tape 2. Find the mass and acceleration of the new system after the peak 3. Add another mass on top of the first 4. Again find the mass and acceleration of this new system 5. Use the force of gravity and determine the normal force 6. Plot a graph of force of friction v normal force in excel 7. Calculate μ for the masses and compare them.

Results Number 1

Fig1a

Fig 1b ( Device at rest for a couple of seconds and then picked up again). Force and Acceleration vs Time Avg force due to gravity= -2.644N Avg force due to acceleration = -9.810 m/s^2 Table 1 (fg) Avg force due to gravity

Avg force due to acceleration (g)

-2.644N

-9.810m/s^2

F=(m)(g) -2.644= (m)(-9.810) m= 0.2695. Mass equals 0.2695 using the equation F=MG

Acceleration= -2.210m/s^2 Figure 2a (Device with push)

Figure 2b ( Device with push zoomed in) ● The acceleration of the device is -2.210m/s^2. ● The device still has an acceleration when I stop pushing it because its kinetic friction is attempting to counter the friction so the object can stop. ● We can find the force by using mass and acceleration due to the equation F=MA.

Number 2- First Mass Added Figure 3 ( Mass Number 2; the iOLab device with another mass added) ● Gives average Force of Gravity

Figure 4 ( Mass Number 2; the iOLab device with another mass added) ● Gives Acceleration of device across y-axis

Table 2 (fg) Avg force due to gravity

Avg force due to acceleration (g)

-2.587N

-9.774 m/s^2

Figure 5 ( Device with the first added mass being pushed)

Acceleration = -2.260m/s^2

Number 3- Second Mass Added

Figure 6 ( Mass Number 3; the iOLab device with a second mass added) ● Gives average Force of Gravity

Figure 7 ( Mass Number 3; the iOLab device with a second mass added) ● Gives Acceleration of device across y-axis

Table 3 (fg) Avg force due to gravity

Avg force due to acceleration (g)

-4.060N

-9.364m/s^2

Figure 8 ( Device with the second added mass being pushed)

Acceleration= -2.718m/s^2

Calculation IoLab Mass Fg=mg (-2.644N) = m(-9.810m/s^2) m= .2695 Mass Number 1 Fg=mg (-2.587N)= m( -9.774) m=.2646

Mass Number 2

Fg=mg (-4.060N)=m(-9.364) m= .4335

Force for iOLAB Mean Acceleration= -2.210 M=.2695 F=ma (-2.210)(.2695)= -0.5955N Force for First Added Mass Mean Acceleration= -2.260 M=.2646 F=ma (-2.260)(.2646)= -0.5979N Force for Second Added Mass Mean Acceleration= -2.718 M=.4335 F=ma (-2.718)(.4335)= -1.178N

Normal Force for iOLab N=mg (.2695)(9.8)= 2.6411N Normal Force for First Added Mass N=mg (.2646)(9.8)= 2.5931N Normal Force for Second Added Mass N=mg (.4335)(9.8)= 4.2483N Table 4 Friction (N)

Normal Force (N)

-0.5955

2.6411

-0.5979

2.5931

-1.178

4.2483

Value for μ iOLab Ff=uFn (-0.5955N)= ux ( 2.6411) u= -0.225 First Added Mass Ff=uFn (-0.5979N)= ux ( 2.5931) u= -0.2305 Second Added Mass Ff=uFn (-1.178N)= ux ( 4.2483) u= -0.2773 Average μ [(-0.225)+(-0.231)+(-0.280)]/(3)= 0.245

Error Analysis IoLab Error Fg= -2.644, σ= 0.029N g= (-9.810/s^2) σ=0.023m/s^2 Using Fg=mg -2.644=m (-9.810) m= .2695 Relative Error for (Fg) (Delta x / x ) (.029/2.644)= .01096 Relative Error for (g) (Delta x/ x) (0.023/9.810)=.002344 Multiplication/Division for Error ∆ S=√( ∆ A/ A )^2 +( ∆B/ B )^ 2 ∆ S=√(0.01096)^2 +(0.0023 )^2 ∆ S=√1.25E^-4 ∆ S=.01119

Analysis Table 5 Gravitati Gravitati onal onal Force (N) Accelerat ion (m/s^2)

Accelerat Mass ion from (kg) Push (m/s^2)

Normal Force (N)

Force of Friction (N)

μ/ Coefficie nt of Friction

iOLab Device

-2.644

-9.810

-2.210

.2695

2.644

0.5955

.225

First mass added

-2.587

-9.774

-2.260

.2646

2.587

0.5979

.231

Second mass added

-4.060

-9.364

-2.718

.4335

4.060

1.178

.280

Discussion The results for our experimentation were consistent with our initial hypothesis. As the mass increases, the force of friction which opposes the actual motion increases as well. Some notable errors that possibly occurred comes from the table surface as well as human error from using the analytics tool in the ioLab. In terms of calculation, we reported an average coefficient of friction of 0.245 and a slope of 0.4019. These two terms are not that far off and we can state that the coefficient of friction calculated vs. my slope on the force of friction vs. normal force are consistent. The slope of Fn and Ff supports the hypothesis stated because it is positive and states that as the normal force increases the frictional force also increases. This is because normal force is able to act on frictional force by pushing the surface of our object and the surface of the table together. The slope represents the coefficient of friction. The mass of our three different systems were calculated by finding the force and acceleration in iOLab and then using the equation F=mg. The forces that were found were the avg force due to gravity and the avg force due to acceleration. After this we pushed the device using the plate and recording the accelerometer. This gave us the peaks as well as the acceleration after the peak. The acceleration after the peak is significant because it represents the acceleration of friction force. Lastly using Newton’s Second Law we used f=ma and found the force of friction. We were able to find the coefficient of friction by using the gravitational force and expression Ff=uFn.

Conclusion In conclusion, the force of friction is a force characteristic that opposes the motion of an object and we can state that as the mass of an object increases this friction also increases. This is

supported by table 5 of our data as the friction increases from 0.5955 to 0.5979 and to 1.178. This is true even though friction is not dependent on the mass of an object but rather the materials it comes in contact with and the force which is able to push surfaces together....