The bunchberry flower has the fastest-moving parts ever observed in a plant. Ini

Question

The bunchberry flower has the fastest-moving parts ever observed in a plant. Initially, the stamens are held by the petals in a bent position, storing elastic energy like a coiled spring. When the petals release, the tips of the stamen act like medieval catapults, flipping through a 60 angle in just 0.29 ms to launch pollen from anther sacs at their ends. The human eye just sees a burst of pollen; only high-speed photography reveals the details. As in the following figure shows, we can model the stamen tip as a 1.0-mm-long, 8.0 g rigid rod with a 8.0 g anther sac at the end. Although oversimplifying, we'll assume a constant angular acceleration.(Figure 1)

How large is the "straightening torque"?

What is the speed of the anther sac as it releases its pollen?

Explanation / Answer

for angular accelaratipn = alpha

revolution

60degree = pi/3 rads = 1.05 rads

alpha = 2*theta / t^2 = 2 * 1.05 / (0.00029s)² = 2.5 x 10^7 rad/s²

moent of inertia
I = (1/3)(8x10^-9kg)(0.001m)^2 + (8x10^-9kg)(0.001m)^2 = 1.07x10^-14 kg·m^2

t = I*alpha = 2.675 x 10^-7 N.m

part b )

wf = wi + alpha*t

wf = 0 + 2.5 x 10^7 * 0.29 x 10^-3

wf = 7250 rad /s

linear speed

v = w*r

v = 7250 * 1 x 10^-3 = 7.25 m/s

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