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Using Newton's Laws: Friction, Circular Motion, Drag Forces - Coggle…
Using Newton's Laws: Friction, Circular Motion, Drag Forces
Friction
Always present when two solid surfaces slide along each other
Kinetic friction
Static friction
Kinetic < Static
Uniform Circular Motion
Motion in a circle of constant radius at constant speed
Instantaneous velocity
Always tangent to the circle
v=rw
Centripetal Acceleration
Always point to center of the circle
a=vw
a=rw^2
a=v^2/r
Centripetal force
Always point to center of the circle
F=mvw
F=mrw^2
F=mv^2/r
Pull force from string will balances out centripetal force to ensure the string will not snap
No centripetal force => Object flies out at tangent to the circle/String snaps
Highway Curves: Banked and Unbanked
Unbanked
Centripetal force toward the center of the circle with friction present
If friction is small(insufficient), car will move nearly in straight line (skidding)
Static friction prevents tires to slip (point towards center of circle and bigger force)
Kinetic friction when tires slip (opposes direction of motion)
Banked
Keeps cars from skidding
Nonuniform Circular Motion
Moving in circular path at varying speeds
Must have tangential component to its acceleration
Velocity-Dependent Forces
Drag force
When object moves through fluid (liquid/air)
Small speed
F approx proportional to v
High speed
F approx proportional to v^2
Terminal velocity
When gravitational force = drag force
Falls in constant v
v=mg/b