Force, friction, and types of friction

Force is a vector quantity that can change the state of motion or shape of an object.
The SI unit of force is the newton (N).
Force is classified into contact forces (e.g., friction, tension) and non-contact forces (e.g., gravitational, electrostatic).
Friction is the resisting force that opposes the motion or tendency of motion between two surfaces in contact.
The direction of frictional force is always opposite to the direction of motion.
Friction is caused by the interlocking of surface irregularities and intermolecular forces between surfaces.
Static friction prevents an object from starting to move and acts when the object is at rest.
The maximum force of static friction is called the limiting friction.
Kinetic friction, also known as sliding friction, acts when an object is in motion.
Rolling friction is the resistance faced by an object rolling over a surface and is much smaller than static or kinetic friction.
The coefficient of friction (μ) is the ratio of the force of friction to the normal force.
Static coefficient of friction (μ_s) is generally higher than the kinetic coefficient of friction (μ_k).
The formula for the maximum static friction is F = μ_sN, where N is the normal force.
The formula for kinetic friction is F = μ_kN.
Normal force is the perpendicular contact force exerted by a surface on an object resting on it.
Air resistance and fluid friction are forms of friction that occur in fluids (liquids and gases).
Friction converts mechanical energy into heat, causing energy dissipation.
Advantages of friction include aiding in walking, gripping objects, and braking in vehicles.
Disadvantages of friction include wear and tear of machinery and loss of energy.
Lubricants are used to reduce friction between moving parts of machinery.
Ball bearings reduce friction by converting sliding motion into rolling motion.
Friction depends on the nature of surfaces and the normal force, but not on the area of contact.
Newton’s First Law relates to friction by explaining how objects tend to stay in their state of rest or motion unless acted upon by an external force.
In inclined planes, friction opposes the component of weight acting parallel to the surface.
The angle of repose is the maximum angle of an inclined plane at which an object remains stationary due to friction.
Dynamic friction includes both sliding and rolling friction.
Fluid friction, or drag, increases with the velocity of an object moving through a fluid.
Streamlining reduces fluid friction by minimizing the resistance offered by the fluid.
The force of friction can be calculated using free-body diagrams and equilibrium equations.
Sliding friction is always less than or equal to static friction for the same surfaces.
Frictional forces are crucial for maintaining traction in vehicles and avoiding skidding.
Friction is independent of the relative velocity between surfaces for small speeds.
The work done against friction is converted into heat energy.
Adhesion at the molecular level contributes significantly to friction.
Friction plays a key role in enabling objects to accelerate, decelerate, or turn.
Devices like anti-lock braking systems (ABS) use the principles of friction for safety.
Frictional force can be experimentally measured using a spring balance.
Wear and tear caused by friction can be minimized by proper lubrication and surface treatments.
Static friction has a self-adjusting nature, increasing to counter external forces up to a limit.
Friction in real-life applications includes walking, driving, and gripping objects securely.
Wheels and rollers are used to reduce friction in transportation systems.
Frictional force is proportional to the weight of the object, as weight affects the normal force.
Frictional heating is utilized in applications like matchstick ignition and vehicle braking.
Excessive friction can lead to energy losses in mechanical systems.
Static equilibrium on inclined planes is determined by balancing frictional and parallel forces.