Question

A 2.1 mm-long, 0.46 mg house flea can reach a height of 17 cm in a single leap.

I've found that, neglecting air speed, v = 1.8 m/s

How do I calculate the kinetic energy of this flea at takeoff & its kinetic energy per kilogram of mass? (to get K = __ J)

Thanks for helping!

Answer 1

(1/2) m v^2 = m g h
v = sqrt (2*9.8*1.7) = 5.77 m/s
(I disagree with your speed)
Ke = (1/2) m v^2 = (1/2)(.46*10^-6 kg)(5.77^2)
= 7.99*10^-6 Joules
divide that by .46*10^-6 to get J/kg
= 16.7 J/kg
which is a lot !