Does body size effect
Jump of the flea
Mass, m = 0.45 mg
Length, l = 1.5 mm
Can a Flea jump 1-2 meters?
At the end of ground contact
Takeoff time is less than 1 ms
Ready to Jump
Hill, A.V. (Nobel Prize 1922) 1950, Dimensions of a
made up of polymers
polymer molecules: a tangled mass of very long spaghetti strands tacked
together to one another in a few widely separated places along the strands
when stretched: tangled mass of polymers stretch out and line up paral
The Spring-Mass Model for Hopping
T/2 = (M/k)0.5
The resonant recoil of the leg spring determines the
ground contact period in hopping
Farley et al., 1991, J. Appl. P
Insect indirect (Asynchronous) ight muscle
Delayed stretch activation + shortening deactivation = oscillatory contractio
Fly thorax is an elastic box:
-Flies beat their wings in a nearly horizontal plane
-Li is generated on
Fibre-reinforced: fibres are embedded in a continous matrix
high toughness, strain energy absorbed at the crack tip.
small flaws are protected from spreading.
much improved with small diameter fibres
Matrix stops crack
Biomeohanioe of Terrestrial Locomotion
1. Metabolic cost of human walking 8. running
2. Inverted pendulum model of walking
3. Spring model of running.
4. Springs reduce the Cost of Transport in running.
Metabolic Power in Human Locomotion
he determined by