Overview

Source: Nicholas Timmons, Asantha Cooray, PhD, room of Physics & Astronomy, school of physical Sciences, college of California, Irvine, CA

The score of this experiment is to examine the physical nature the the two types of friction (i.e., static and kinetic). The procedure will include measuring the coefficients of friction for objects slide horizontally and also down an inclined plane.

You are watching: How can the frictional force be experimentally determined

Friction is not fully understood, however it is experimentally identified to be proportional to the normal pressure exerted on an object. If a microscope zooms in on two surfaces that are in contact, that would disclose that their surfaces are an extremely rough on a little scale. This stays clear of the surfaces from conveniently sliding past one another. Combining the impact of turbulent surfaces through the electric forces in between the atoms in the products may account because that the frictional force.

There space two types of friction. Revolution friction is present when an object is no moving and also some force is required to obtain that object in motion. Kinetic friction is present when an item is currently moving yet slows down because of the friction in between the sliding surfaces.


Principles


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*
Figure 1.

Figure 1 shows four forces acting on things that sits on a horizontal plane.

*
coincides to some used horizontal force.
*
is the pressure of gravity on the object, i m sorry is suitable equally but in the opposite direction by the regular force, . The normal force is a result of a surface ar acting on an item in opposition to gravity. The typical force describes why a publication does no simply loss through the table that is relaxing upon. Finally, the contrary the applied force is the frictional force, . The frictional force is proportional to the normal force:

*
, (Equation 1)

where is the coefficient the friction.

The coefficient that friction should be measure experimentally and is a residential property that relies upon the two materials that are in contact. There are two species of coefficients the friction: kinetic friction, , once objects are already in motion, and static friction, , once objects room at rest and require a specific amount of pressure to obtain moving. For an object sliding follow me a path, the normal force is same to the load the the object. Therefore, the frictional pressure depends only upon the coefficient and also the mass of an object.

If the thing is on an skinny plane, then the normal pressure is perpendicular come the incline and also is not equal and also opposite to the weight as can be checked out in Figure 2.

*
Figure 2.

In this case, just a ingredient of is identical to the regular force, depending on the angle θ:

*
. (Equation 2)

The angle of repose

*
is defined as the point at i m sorry the pressure of heaviness on an item overcomes the static friction force and also the object begins to slide under an lean plane. A great approximation for the edge of repose is:

*
. (Equation 3)

In this lab, two metal pans will be supplied to represent materials with various coefficients that friction. Block A will have a sand paper bottom, which will an outcome in a greater coefficient the friction, when block B will have a smooth steel bottom.


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Procedure


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1. Measure the coefficients of friction.

Add a 1,000-g load to each block and use a range measure the masses of blocks A and also B, consisting of the included mass.Connect the force scale to block A. Pull the scale horizontally and note the analysis just prior to the block starts to slide. Just before it starts to slide, the maximum lot of revolution friction is resisting the movement. Use the force reading to calculation for block A. Perform this 5 times and record the typical value.Repeat action 1.2 v block B.Pull block A across the table at a constant speed. If the rate is constant, climate the force reading ~ above the scale have to be same to the friction force. Calculate for block A. Do this 5 times and also record the median value.Repeat action 1.4 with block B.

2. Result of load on the pressure of friction.

Place block A on optimal of block B and also repeat action 1.4 five times, identify the average value. Calculate the factor through which the frictional force increased/decreased.Place block B on optimal of block A and also repeat action 1.4 five times, identify the mean value. Calculate the factor whereby the frictional pressure increased/decreased.

3. Result of surface area on pressure of friction.

Turn block B onto the next that contains only the pickled in salt of the pan. The weight will should be inserted on the peak of the face-up side. Measure up the pressure of friction and compare it to the worth measured in step 1.2. Calculation the factor through which the frictional pressure increased/decreased.

4. Edge of repose.

Place block A ~ above the adjustable incline plane, starting at an angle of 0°. Slowly raise the angle till the block starts to slide. Making use of a protractor, measure the angle of repose and also use Equation 3 to calculate the coefficient of static friction just prior to the block started to slide. Perform this five times and record the median value.Repeat step 4.2 v block B.

The impacts of friction are easily observed in everyday tasks and however the physical mechanisms that govern friction can be complex.

Friction is a force that opposes the movement of things when that is in call with a surface. At the microscopic level, the is brought about by surface roughness of the products in contact and intermolecular interactions. Yet one have the right to overcome this force by applications of an exterior force that is equal in magnitude.

The score of this video clip is to demonstrate how to measure friction in a lab setup for objects slide horizontally and also down an lean plane.


Before diving right into the protocol, let"s revisit the principles behind the frictional force. First, you need to know that there are two species of frictions - kinetic friction and static friction.

To recognize kinetic friction, imagine you space in a rubber pipe sliding across an limitless horizontal field of ice.

Although ice may be taken into consideration a smooth surface, if us look in ~ the microscopic level, over there are complex interactions in between the 2 surfaces that reason friction. These interactions count on surface roughness and attractive intermolecular forces.

The size of this kinetic friction pressure is same to the product that the coefficient of kinetic friction, or μK, which counts on the material-surface combination, and the common force, or Fnorm the pushes the object and surface together.

Fnorm action to support the object and also is perpendicular to the interface. In this case, because the pipe is ~ above a level ground, the Fnorm is same to and opposite the pressure of gravity, i beg your pardon is mg. Therefore, if you recognize the combined mass that you through the tube, and also the coefficient the kinetic friction because that rubber and also ice, we can conveniently calculate the pressure of friction.

Kinetic friction can convert some that the tube"s kinetic energy into heat and will additionally reduce the inert of the tube at some point bringing it come rest.

Now, this is once static friction - the other kind of friction - comes into play. This frictional pressure opposes motion of a revolution object and could be calculated by applying an outside force. The used force that ultimately moves the object reveals the maximum static force.

The formula for maximum static pressure is the same as the one for kinetic friction, yet the coefficient of revolution friction μS is generally greater than μK because that the exact same material-surface combination.

Another means to overcome the best static pressure is by increasing the slope of the surface. At part angle, called the angle of repose or θR, the force pulling down the slope will certainly equal the static friction force and the tube will start to slide. This pulling force, i m sorry is the sine of the angle of repose times the force of gravity, equates to the maximum revolution force, i beg your pardon is μS times product of m, g, and also cosine that θR. By rearranging this equation, we have the right to calculate the coefficient of static friction.


Now that we"ve learned the values of friction, let"s see just how these concepts can be applied to experimentally calculate the forces and also coefficients that both kinetic and static friction. This experiment consists of a fixed scale, a force scale, two steel pans with different coefficients of friction denoted as block 1 and also 2, an flexible incline plane, 2 1000 g weights, and a protractor.

Add a 1000 g load to every block and also use the scale to measure up the masses that the loaded blocks.

After connecting the pressure scale to block 1, pull the range horizontally and note the force reading just prior to the block begins to slide. Document this maximal revolution friction force and also repeat this measurement 5 times to achieve multiple data sets. Perform the very same procedure utilizing block 2 and also record this values.

Next, with the pressure scale associated to block 1, traction the scale at a constant speed and also note the kinetic friction force on the gauge. Repeat this measurement five times to acquire multiple data sets. Again, perform the exact same procedure using block 2 and record these values.

Now, ar block 1 on peak of block 2 and also pull the scale at a constant speed to determine the kinetic friction force. Repeat this measurement five times and also calculate the average. Then carry out the very same procedure v block 2 on height of block 1.

For the next experiment, revolve block 1 such that the smaller surface area faces the table and also attach it to the force scale. Now measure the revolution friction pressure as before by making keep in mind of the force before the block starts to slide. Repeat this measurement 5 times to obtain multiple data sets.

For the last experiment, place block 1 ~ above the adjustable incline aircraft with the airplane initially in ~ an angle of zero degrees. Gradually raise the angle of the plane and use a protractor to recognize the edge at i m sorry the block begins to slide. Again, repeat this measurement 5 times to achieve multiple data sets and also perform the exact same procedure making use of block 2.


For the experiments performed ~ above horizontal surface, the normal force on the block is same to the weight, the is mass time g. Due to the fact that the fixed of block 1 and 2 because that both static and also kinetic friction experiments space the same, Fnorm is the same in all four cases. Making use of the mean of the measured pressure values for the assorted experiments, and also the formulae for both frictions, the coefficients that friction have the right to be calculated.

As expected, the coefficient of static friction is better than the coefficient that kinetic friction. Furthermore, the respective coefficients because that the two blocks space different due to the fact that they each possess a various surface roughness.

In the stacked blocks experiment, we know that the fixed doubles in both cases, therefore we have the right to calculate the new Fnorm. We already know μk for the block in contact with the surface. Utilizing this we deserve to calculate the kinetic friction force, which agrees well v the measure up force throughout the experiment.

The friction pressure measured complying with a readjust in orientation that block 1 demonstrated that the call surface area walk not impact the force of friction. The discrepancies between the calculated and measured pressures are regular with the estimated errors linked with reading the force scale while preserving a constant speed.

For the inclined aircraft experiments, the angle of repose was measured. Utilizing this angle, the coefficients of revolution friction could be determined, and also here the values compare favorably v the coefficients measured indigenous the horizontal slide measurements.


Studying friction is necessary in numerous applications, as it have the right to either be highly beneficial or a phenomenon that must be minimized.

It is extremely important for car tire manufactures to examine friction, as it permits tires to obtain traction top top a road. Therefore, when it rains, the water and residual oils on the road substantially reduce the coefficient of friction, making slide and crashes much more likely.

While designers want to rise friction for car tires, because that engines and machinery in basic they desire to minimize it, together friction between metals deserve to generate heat and also damage your structures. Therefore, engineers constantly examine lubricants that may help in diminish the coefficient that friction in between two surfaces.


You"ve simply watched chathamtownfc.net"s introduction to Friction. You need to now know what factors add to the magnitude of friction, the different types of friction, and the underlying physics mechanisms that govern it. As always, thanks for watching!


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 Table 1. Coefficients of friction.

Block
A0.680.60
B0.520.47

Table 2. Result of weight and surface area on the pressure of friction.

Measurement(N)Factor whereby it is bigger or smaller
Block B on A16With from step 1.4 = 2.3
Block A ~ above B14With  from action 1.5 = 2.5
Small surface area5With  from step 1.4 = 0.9

Table 3. Angle of repose.

BlockAngle the repose
*
(°)
A300.58
B240.45

The results acquired from the experiment match the predictions make by Equations 1 and also 2. In step 1, the static friction was larger than the kinetic friction. This is constantly the case, as much more force is compelled to get over friction when an object is not already in motion. In action 2, the was shown that the pressure of friction to be proportional come the weight of both blocks and also the coefficient the kinetic friction that the block in call with the table. The an outcome of step 3 confirms the the surface area walk not influence the pressure of friction. In step 4, the edge of repose have the right to be approximated through Equation 3. The error connected with the lab originates from the challenge of reading the force scale while keeping a consistent velocity because that the slide block. By taking several measurements and calculating the average, this impact can it is in reduced.


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Friction is all over in our everyday lives. In fact, it would certainly not be possible to walk without it. If who tried wade on a frictionless surface, he would certainly go nowhere. The is just the friction between the bottom that his feet and the ground together his muscles push versus the ground that propels that forward.

In virtually every facet of industry, engineers are do the efforts to reduce friction. Once two surfaces space in contact, over there will always be friction. This can take the form of heat, such together the warmth felt once someone conveniently rubs her hands together. In commercial applications, this heat can damage machines. Friction forces additionally oppose the motion of objects and also can sluggish done mechanically operations. Therefore, substances choose lubricants are used to diminish the coefficient of friction between two surfaces.

Table 4. Instance coefficients of friction.

Materials
wood top top wood0.2
brass on steel0.44
rubber ~ above concrete0.8
lubricated sphere bearings

In this experiment, the coefficients of static and also kinetic friction were measured for two various sliding blocks. The effect of massive on the force of friction to be examined, along with the impact of surface ar area. Lastly, the edge of repose because that a block on one inclined plane was measured.


The impacts of friction are quickly observed in everyday activities and however the physics mechanisms that govern friction have the right to be complex.

Friction is a force that opposes the activity of an object when it is in call with a surface. At the microscopic level, that is resulted in by surface roughness of the materials in contact and intermolecular interactions. But one have the right to overcome this force by applications of an external force the is same in magnitude.

The goal of this video clip is to show how to measure up friction in a lab setup for objects sliding horizontally and also down an inclined plane.

Before diving into the protocol, let"s revisit the principles behind the friction force. First, you require to understand that there space two species of frictions - kinetic friction and also static friction.

To know kinetic friction, imagine you room in a rubber pipe sliding across an limitless horizontal ar of ice.

Although ice might be considered a smooth surface, if us look in ~ the microscope level, over there are complicated interactions between the 2 surfaces that cause friction. These interactions count on surface roughness and also attractive intermolecular forces.

The size of this kinetic friction force is equal to the product that the coefficient the kinetic friction, or μK, which depends on the material-surface combination, and the regular force, or Fnorm that pushes the object and also surface together.

Fnorm acts to assistance the object and is perpendicular come the interface. In this case, because the pipe is top top a level ground, the Fnorm is equal to and also opposite the pressure of gravity, i beg your pardon is mg. Therefore, if you understand the merged mass of you through the tube, and the coefficient the kinetic friction for rubber and ice, us can quickly calculate the force of friction.

Kinetic friction can convert some of the tube"s kinetic energy into heat and will also reduce the inert of the tube eventually bringing it come rest.

Now, this is when static friction - the other form of friction - comes right into play. This frictional force opposes motion of a revolution object and could it is in calculated by applying an external force. The applied force that eventually moves the object reveals the maximum revolution force.

The formula because that maximum static force is the very same as the one for kinetic friction, yet the coefficient of revolution friction μS is generally greater than μK for the same material-surface combination.

Another way to overcome the maximum static pressure is by enhancing the steep of the surface. At part angle, referred to as the angle of repose or θR, the pressure pulling under the slope will certainly equal the revolution friction force and the pipe will begin to slide. This pulling force, i beg your pardon is the sine of the edge of repose time the pressure of gravity, equals the maximum revolution force, which is μS time product the m, g, and also cosine of θR. By rearranging this equation, we have the right to calculate the coefficient of revolution friction.

Now the we"ve learned the ethics of friction, let"s see just how these concepts can be applied to experimentally calculate the forces and also coefficients the both kinetic and also static friction. This experiment is composed of a mass scale, a force scale, two steel pans with different coefficients of friction denoted together block 1 and 2, an adjustable incline plane, 2 1000 g weights, and a protractor.

Add a 1000 g weight to each block and also use the scale to measure the masses the the invited blocks.

After connecting the pressure scale to block 1, pull the range horizontally and also note the pressure reading just before the block begins to slide. Record this maximal static friction force and also repeat this measurement five times to achieve multiple data sets. Execute the very same procedure utilizing block 2 and also record this values.

Next, v the force scale associated to block 1, traction the scale at a consistent speed and also note the kinetic friction pressure on the gauge. Repeat this measurement 5 times to obtain multiple data sets. Again, do the very same procedure using block 2 and record these values.

Now, ar block 1 on top of block 2 and pull the scale at a constant speed to determine the kinetic friction force. Repeat this measurement 5 times and also calculate the average. Then do the exact same procedure through block 2 on top of block 1.

For the following experiment, rotate block 1 such that the smaller surface area encounters the table and also attach it come the pressure scale. Currently measure the static friction force as before by making note of the force prior to the block starts to slide. Repeat this measurement 5 times to attain multiple data sets.

For the critical experiment, ar block 1 ~ above the flexible incline plane with the airplane initially in ~ an edge of zero degrees. Slowly raise the edge of the aircraft and usage a protractor to recognize the edge at which the block begins to slide. Again, repeat this measurement 5 times to acquire multiple data sets and also perform the very same procedure utilizing block 2.

For the experiment performed ~ above horizontal surface, the normal force on the blocks is equal to the weight, the is mass time g. Since the fixed of block 1 and also 2 for both static and kinetic friction experiments space the same, Fnorm is the exact same in all 4 cases. Utilizing the median of the measured force values for the miscellaneous experiments, and the formulae for both frictions, the coefficients the friction have the right to be calculated.

As expected, the coefficient of revolution friction is better than the coefficient the kinetic friction. Furthermore, the particular coefficients because that the 2 blocks space different since they each possess a various surface roughness.

In the stacked blocks experiment, we understand that the mass doubles in both cases, therefore we can calculate the brand-new Fnorm. We already know μk for the block in contact with the surface. Using this we can calculate the kinetic friction force, which agrees well through the measure force throughout the experiment.

The friction force measured following a change in orientation that block 1 demonstrated that the contact surface area does not affect the pressure of friction. The discrepancies between the calculated and measured pressures are regular with the estimated errors connected with reading the force scale while preserving a constant speed.

For the inclined plane experiments, the edge of repose was measured. Utilizing this angle, the coefficients of revolution friction might be determined, and here the worths compare favorably v the coefficients measured from the horizontal sliding measurements.

Studying friction is important in several applications, together it can either be highly useful or a phenomenon that must be minimized.

It is extremely vital for auto tire manufactures to research friction, as it permits tires to gain traction top top a road. Therefore, once it rains, the water and also residual oils on the road considerably reduce the coefficient of friction, making sliding and accidents much more likely.

See more: What Does The Name Whitney Mean Ing, Popularity And Info On Babynames

While engineers want to rise friction for automobile tires, because that engines and also machinery in general they desire to mitigate it, as friction in between metals have the right to generate heat and also damage your structures. Therefore, engineers constantly examine lubricants that may help in decreasing the coefficient that friction between two surfaces.

You"ve just watched chathamtownfc.net"s advent to Friction. You should now understand what factors add to the size of friction, the different varieties of friction, and also the underlying physics mechanisms the govern it. Together always, many thanks for watching!