What are some basic formulas and examples for friction and forces?

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Basic formulas for understanding forces and friction include Newton's laws, which are essential for linear dynamics. Newton's 1st Law states that the sum of forces equals zero when an object is at constant velocity. The 2nd Law relates the sum of forces to mass and acceleration, while the 3rd Law emphasizes action-reaction pairs. The friction force can be calculated using the formula F_f = μN, where μ is the coefficient of friction and N is the normal force. Mastering these concepts and practicing Free Body diagrams will be crucial for success in tests on forces and friction.
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Hello, I'm on my way to having a test on "Forces/Friction" very soon in the future, but the thing is I am stuck :( my teacher won't really help me out. He only states the answer doesn't show how to achieve it at all. So I was wondering if anyone could tell me some basic formulas, and examples that could help me out?


Thanks John
 
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All you need to learn for Linear Dynamics, also learn how to do Free Body diagrams.

Newton's 1st Law

\sum_{i=1}^{n} \vec{F}_{i} = 0 \rightarrow \vec{v} = constant

Newton's 2nd Law

\sum_{i=1}^{n} \vec{F}_{i} = m \vec{a}

Newton's 3rd Law

\vec{F}_{12} = -\vec{F}_{21}

Friction Force Magnitude

F_{f} = \mu N
 
WOW same here..i am having a test on friction/forces very soon too! and i also got a teacher dat sucks!
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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