Linear Kinetics 4 Flashcards
perfectly elastic collision characteristics
kinetic energy conserved
perfect inelastic Collison characteristics
maximal kinetic energy is lost
Coefficient of restitution equation (E)
E = square root of KE after collision / KE before collision
E= V1-V2 / U1-U2
What is newtons law of impact?
2 bodies travelling towards each other, the difference in velocity after impact is constant to different at impact
(V1-V2) = E (U1-U2)
Collisions with earth equations (V1 & U1 = 0)
E= V2 / U2
Experimental determination of coefficient of restitution equations (U1 & V1)
U1 = square root 2gH(b)
V1 = square root 2gH(d)
g = gravitational acceleration Hb = bounce height Hd = drop height
Final coefficient of restitution equation
E = square root Hb / Hd
Friction defintion
When one body moves or tends to move across the surface of another body the force that opposes motion or impending motion is friction
When is increased friction good in sport
gymnastics - chalk - ^ grip
surfers - wax board - ^ grip
table tennis - rubber paddle to increase spin
Shoes - ^ grip
When is decreased friction food in sport
Ice sports - slide/glide
skateboard - wax
When is friction needed to be not too much nor too little in sport
clay tennis courts
golf clubs/balls
What is sliding friction
the that opposes sliding motion between the surfaces of two objects
what is rolling friction
the frictional force that occurs when one object rolls over the surface of another
Sliding friction equations
P = force applied F = friction force R = reaction force
P = F = no movement
P > F = sliding
Coefficient of friction equation (U)
U = F / R
describes the ratio of force of friction between the bodies
