Rio Salado College Lab 5 PDF

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Summary

Introduction to mechanics, heat and sound. This is an algebra-trigonometry based course suitable for college-transfer students in pharmacy, pre-dental and pre-medical programs who do not need a calculus-based physics course....

Description

Katy Waterman PHY 111 09/05/2021 Lab 5 – Unbalanced Forces Lab Purpose/Question The purpose of this lab is to explore the relationship between the normal force of an object and the size of the friction force exerted on the object. Materials -

Spring scale, friction block, string, random objects of assorted weight and flat uniform surface

Procedures 1. Calibrate the spring scale and hold it vertically making sure the scale reads 0 N when there is nothing suspended from your scale. 2. The upward normal force is equal to the downward gravity force. Find the initial weight of the block. Suspend the friction block from the spring scale and record the weight. Make sure to read the weight and not the mass. 3. Find a flat surface to work on, place the friction block down and connect the spring scale making sur that the force (newton) side is face up. Using the spring scale to drag the block at a constant speed across the surface. Record the force of the pull. If motion was at a constant speed, this applied force is equal to the kinetic friction force. 4. Find an object that can be placed onto the friction block to increase the total weight and hang the object from the spring scale to find its weight. Add this weight to the original block weight and record the total weight. 5. Place the object on top of the block and use the spring scale to drag the block system at a constant speed across the surface. The speed doesn’t need to be the same, it is unimportant. Record the force for this new trial.

Katy Waterman PHY 111 09/05/2021 6. Repeat this increasing the weight each time. Collect at least 5 data points and repeat each of those multiple times and then take the average of each. 7. Create a data table and scatter plot graph in excel. Put the friction force of the vertical axis and the weight on the horizontal axis. Your graph should include a trendline and an equation. Photograph of experiment

Data Initial weight of the block: 1.1 N Force of pull of the block: 0.5 N Initial weight of the bread pack: 2.3 N Force of pull of the bread pack: 1.2 N Initial weight of set of keys: 0.7 N Force of pull of the set of keys: 0.6 N Initial weight of coffee cup: 4 N

Katy Waterman PHY 111 09/05/2021 Force of pull of coffee cup: 1.3 N Initial weight of mini flashlight: 0.5 N Force of pull of mini flashlight: 0.3 N Initial weight of tape dispenser: 0.3 N Force of pull of tape dispenser: 0.5 N

Calculations and Graphs

Katy Waterman PHY 111 09/05/2021

Results As a result of this lab, the weight with the block vs. the friction force of pull produced a positive slope linear trendline with an equation of y=0.2609x+0.0861. Conclusion This lab was centered around the idea that friction is a resistive force created when two objects rub against each other. Friction acts parallel to the surfaces of the two objects. This lab focused on the idea that pulling the block with the object on it at a constant speed is what was important and the actual speed at which the object is being pulled is unimportant. After looking at the data, the more an object weighs the higher the friction force turned out to be. This makes sense in that if an object is heavier, it requires more of a force to pull that object across a surface. The scatter plots were all over the graph but did produce a positive slope linear trendline shown through the graph and the equation of the graph. Analysis Questions Response 1. Does the speed of the moving object affect the amount of kinetic friction on the object? Explain your answer and cite evidence to support your claim. -

No, the speed of the moving object does not affect the amount of kinetic friction on the object. A constant speed is more important than what the speed is. As stated in the lesson, a constant force needs to be applied in order to cancel out the friction force. If the motion was at a constant speed, the applied force is equal to the kinetic friction force.

2. What is the experimentally determined coefficient of friction between your friction block and your chosen surface? Is this a reasonable value? Explain your answer.

Katy Waterman PHY 111 09/05/2021

References Urone, P. P. (2017). College physics Vol. 1. OpenStax....