eloquent logic - dynamics

Legend

F_net	=	net force
m	=	mass
a	=	acceleration
F_g	=	force of gravity
F_f	=	force of friction

網上實驗

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Coefficient of Friction

Purpose:
	Calculate the coefficient of table and masses using simple devices.
Material:	masses (1 kg, 500 g, 100 g, 50 g)
	string
	pulley

Setup:	Apparatus setup as below diagram.

Background info & calculations:

Since there two masses involved at the same time, we name the mass on the table m₁ and the hanging mass m₂ . This way we can distinguish them in the equations.

F_f = F_g= m₂g

At the same time.
F_f = F_N = m₁g

Therefore:
m₂g = m₁g
= m₂/m₁

_{However, there is one condition we have to consider,}F_fmust equal F_g(m₂g). This means that the system must be moving at constant speed, since there's no net force, and in turn no acceleration.

Loooking at the forces that acts on the system, we ignored air resistance. F_g, m₁g cancels out with F_N and rope tension cancels each other out since they're going in different directions.

Experiment:
	Click on the different size masses below to see experiment.

Calculation:

Using the second mass for calculation, we get:

= m₂/m₁

= 100 g / 500 g = 0.20

Conclusion:
	The kinetic coefficient of friction is 0.20. The factors that could affect this experiment is that the string is not weightless and the pulley is not frectionless. The concept of Newton's first law was also experienced. Objects more or remain in the same way, as long as no net force acts on it.

Inclined Plane

Formulas