Determining the static and kinetic coefficients on an incline of wood on wood

In summary, for a lab task, the static and dynamic coefficients of friction for a block of wood on a plank of wood were determined. In part A, the angle at which the block started to move was found to be 45.4 degrees, giving a static coefficient of 1. In part B, the angle was increased to 50 degrees and the time for the block to cover a distance of 1 meter was recorded as 0.69 seconds. However, the calculation for the kinetic coefficient is unknown and further research is needed. The kinematic equations may be a good starting point for determining the acceleration and velocity.
  • #1
cmcc3119
16
2

Homework Statement



This was a lab task in which we are asked: Determine the static and dynamic coefficients of friction for a block of wood of mass 82.2grams on a plank of wood.

PART A:
To determine the static coefficient we found the angle at which point the block just started to move. This was 45.4 degrees.

For Part A, I used the equation fr = tan 45.5 degrees which gave me an answer of 1. I am not sure if this is to be expected static coefficient of a polished block of wood on a plank of wood as anything else I have read has always had a lower coefficient.

PART B:
To determine the kinetic coefficient we increased the angle to 50 degrees and timed how long the block took to cover the plank, a distance of 1 meter, when released from the top. The average time was found to be 0.69s. This is where I get stuck! I do not know how to calculate the kinetic coefficient and after much research on the net I am still as stuck as I first was... The block is accelerating but I don't know how to determine the acceleration or whether that is even necessary. Furthermore, can I just state the velocity is 0.69ms-1?
Can someone please just suggest a starting point...
 
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  • #2
Try the kinematic equations, they're the ones that relate time, distance, velocity and acceleration when the acceleration is constant.
 
  • #3


I would approach this task by first understanding the concepts of static and kinetic friction. Static friction refers to the force that needs to be overcome to initiate movement between two surfaces, while kinetic friction refers to the force that resists the movement of two surfaces that are already in motion.

For Part A, you correctly used the equation fr = tan θ to determine the static coefficient of friction. This value of 1 may seem high, but it is within the range of values for wood on wood surfaces. It is important to note that the coefficient of friction can vary depending on factors such as surface roughness and moisture content.

For Part B, to determine the kinetic coefficient of friction, you will need to use the equation F = ma, where F is the force of friction, m is the mass of the block, and a is the acceleration. In this case, the acceleration can be calculated using the equation a = Δv/Δt, where Δv is the change in velocity (final velocity - initial velocity) and Δt is the change in time.

In your experiment, the block is released from rest at the top of the incline, so the initial velocity is 0. The final velocity can be calculated using the distance and time measurements. In this case, the final velocity would be 1m/0.69s = 1.45 m/s.

Then, the acceleration can be calculated as a = (1.45 m/s - 0 m/s)/0.69 s = 2.1 m/s^2.

Finally, using the equation F = ma, the kinetic coefficient of friction can be calculated as μk = F/m = (m x a)/m = a. In this case, μk = 2.1 m/s^2.

It is important to note that the value of the kinetic coefficient of friction may be slightly different from the static coefficient, as the surfaces may have a different level of roughness and moisture content when in motion compared to when at rest.

I hope this helps guide you in your calculations and understanding of the experiment. It is always important to thoroughly research and understand the concepts and equations before conducting a scientific experiment.
 

1. What is the purpose of determining the static and kinetic coefficients on an incline of wood on wood?

The purpose of determining the static and kinetic coefficients on an incline of wood on wood is to understand the frictional behavior between two wooden surfaces that are in contact with each other. This information can be useful in various applications, such as designing machinery or predicting the movement of objects on inclined surfaces.

2. How do you measure the static and kinetic coefficients on an incline of wood on wood?

The static and kinetic coefficients can be measured by conducting experiments on an inclined plane with two wooden surfaces in contact. The angle of the incline and the weight of the object placed on it can be adjusted to record the minimum angle at which the object starts to slide (static coefficient) and the angle at which the object slides at a constant speed (kinetic coefficient).

3. What factors can affect the static and kinetic coefficients on an incline of wood on wood?

The static and kinetic coefficients can be affected by various factors, such as the roughness and surface texture of the wooden surfaces, the weight and size of the object, and the angle of the incline. Other factors, such as temperature and humidity, can also influence the coefficients.

4. What are the applications of the static and kinetic coefficients on an incline of wood on wood?

The static and kinetic coefficients have practical applications in engineering and physics. They can be used to design and optimize machinery that involves sliding or rolling objects on inclined surfaces. They can also be used to predict the movement and stability of objects on inclined planes, such as cars on hilly roads or skiers on snowy slopes.

5. How do the static and kinetic coefficients on an incline of wood on wood differ from other surface combinations?

The values of the static and kinetic coefficients on an incline of wood on wood may differ from other surface combinations due to variations in surface roughness, weight, and angle of the incline. Different materials also have different coefficients of friction, so the values may vary depending on the type of surfaces in contact.

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