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Exercise 2.4.6: Suppose you wish to measure the friction a mass of 0.1 kg experiences as it slides along a floor (you wish to find c). You h
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Exercise 2.4.6: Suppose you wish to measure the friction a mass of 0.1 kg experiences as it slides along a floor (you wish to find c). You have a spring with spring constant k 5 N/m. You take the spring, you attach it to the mass and fix it to a wall. Then you pull on the spring and let the mass go. You find that the mass oscillates with frequency 1 Hz. What is the friction
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5 years
2021-08-05T04:48:52+00:00
2021-08-05T04:48:52+00:00 1 Answers
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Answer:
b = 0.6487 kg / s
Explanation:
In an oscillatory motion, friction is proportional to speed,
fr = – b v
where b is the coefficient of friction
when solving the equation the angular velocity has the form
w² = k / m – (b / 2m)²
In this exercise we are given the angular velocity w = 1Hz, the mass of the body m = 0.1 kg, and the spring constant k = 5 N / m. Therefore we can disperse the coefficient of friction
let’s call
w₀² = k / m
w² = w₀² – b² / 4m²
b² = (w₀² -w²) 4 m²
Let’s find the angular velocities
w₀² = 5 / 0.1
w₀² = 50
w = 2π f
w = 2π 1
w = 6.2832 rad / s
we subtitute
b² = (50 – 6.2832²) 4 0.1²
b = √ 0.42086
b = 0.6487 kg / s