High speed video footage has been used to study how fleas are so good at jumping. One particular video shows a 220-g flea begin to jump vertically upwards from a standing start. The video shows the launch only: the whole time (1.20 ms) the flea is still in contact with the ground. At the end of the launch, with its legs fully extended, but feet still touching the ground, the flea's body has moved upwards by 0.706 mm and is travelling upwards at 1.18 m/s.

1) Draw a free body diagram of the flea's body in the box. Add a coordinate system. Write your knowns and unknowns on the picture of the flea.

force and kinematics: Calculate the acceleration of the flea's body and work out the force exerted on the body by the legs.

work and energy: Calculate the change of kinetic energy of the flea's body and work out the force exerted on the body by the legs.

impulse and momentum: Calculate the change of momentum of the flea's body and work out the force exerted on the body by the legs.

The flea uses a pad of an elastic polymer (elastomer) called resilin as a kind of catapult mechanism to store energy and then release it very quickly to make the jump. What is the effective spring constant of the flea's resilin? (Resilin is the kind of material that we wish we could make as well as Nature does. The efficiency of the recovery of stored elastic potential energy is 97%.) List the objects you must include in your system to do a conservation of energy analysis: Then draw BEFORE and AFTER pictures:

Then do the analysis: