M1: Forces and Equilibrium
1. Types of Forces
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Weight (W): The force due to gravity acting vertically downward.
Normal Reaction (R): The support force from a surface, acting perpendicular to the surface.
Tension (T): The pulling force in a string or rope.
Friction (F): The force that opposes motion between two surfaces in contact.
Diagram: Block on Horizontal Surface
R
W
2. Equilibrium
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A body is in equilibrium when the resultant force acting on it is zero.
For equilibrium: Sum of horizontal forces = 0.
For equilibrium: Sum of vertical forces = 0.
3. Resolving Forces
If a force F acts at an angle θ to the horizontal: Horizontal component = F cos θ Vertical component
= F sin θ
Diagram: Force at an Angle
F
Vertical
Horizontal
4. Friction
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Friction opposes motion.
Limiting friction = µR.
µ is the coefficient of friction.
R is the normal reaction.
End of Notes