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ellomoto135
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What are the equations that can be used to calculate friction, be detailed i don't know much about.
What are the equations to calculate friction
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Friction can be calculated using different equations depending on the state of motion of the surfaces involved. For stationary surfaces, the friction force is part of the reaction force. When surfaces are moving, the friction force is determined by the kinetic coefficient of friction (µk) multiplied by the normal force (N). If the surfaces are about to move, the static coefficient of friction (µs) is used instead, also multiplied by the normal force. Understanding these coefficients is essential for accurate friction calculations.
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tiny-tim
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welcome to pf!
hi ellomoto135! welcome to pf!
there isn't much to say …
if the surfaces aren't moving, and aren't "about to move", the friction force is simply part of the reaction force … you calculate it exactly as if the surfaces were fixed together
if they are moving, you have to look up the kinetic (dynamic) coefficient of friction, µk, in a table (or it'll be given in an exam question), and then …
if they are "about to move", you have to look up the static coefficient of friction, µs, in a table (or it'll be given in an exam question), and then …
hi ellomoto135! welcome to pf!
there isn't much to say …
if the surfaces aren't moving, and aren't "about to move", the friction force is simply part of the reaction force … you calculate it exactly as if the surfaces were fixed together
if they are moving, you have to look up the kinetic (dynamic) coefficient of friction, µk, in a table (or it'll be given in an exam question), and then …
the friction force is µkN (where N is the normal force)
if they are "about to move", you have to look up the static coefficient of friction, µs, in a table (or it'll be given in an exam question), and then …
the friction force is µsN (where N is the normal force) 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19.
For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Figure 1 Overall Structure Diagram
Figure 2: Top view of the piston when it is cylindrical
A circular opening is created at a height of 5 meters above the water surface. Inside this opening is a sleeve-type piston with a cross-sectional area of 1 square meter. The piston is pulled to the right at a constant speed. The pulling force is（Figure 2）： F = ρshg = 1000 × 1 × 5 × 10 = 50,000 N.
Figure 3: Modifying the structure to incorporate a fixed internal piston
When I modify the piston...
Let's declare that for the cylinder,
mass = M = 10 kg
Radius = R = 4 m
For the wall and the floor,
Friction coeff = ##\mu## = 0.5
For the hanging mass,
mass = m = 11 kg
First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on.
Force on the hanging mass
$$mg - T = ma$$
Force(Cylinder) on y
$$N_f + f_w - Mg = 0$$
Force(Cylinder) on x
$$T + f_f - N_w = Ma$$
There's also...
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