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Unformatted text preview: then essential. 1. What is his acceleration?
2. What force does Earth exert on Igor? A car of mass m moves at a constant speed v of 20m/s
around a banked circular track of radius R=190m. If the
frictional force from the track is negligible, what bank angle
θ prevents sliding. The
The Department of Physics, CUHK The Department of Physics, CUHK
17 18 3 §6. Review & Summary Review & Summary
Drag force: when there is a relative motion between air and a
body, the body experiences a drag force. Friction: when a force tends to slide a body along a surface,
a frictional force from the surface acts on the body.
1. 2. D = 1 C ρ Av 2
2 If the body does not move, then the static frictional force fs and the
component of F which is parallel to the surface are equal in
magnitude and opposite in direction.
The magnitude of fs has a maximum f s , max = µ s FN
3. Terminal speed µ s coefficient of static friction 1
2 If the body begins to slide along the surface, the magnitude of fk is f k , max = µ k FN C ρ Av 2 − Fg = 0
t vt = 2 Fg
C ρA µk coefficient of kenetic friction The Department of Physics, CUHK The Department of Physics, CUHK
19 20 Review & Summary
Uniform circular motion: if a particle moves in a circle at
constant speed, the particle is said to be in uniform circular
motion. a= v2
R F =m v2
R The Department of Physics, CUHK
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