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 0.27 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, 12 ?g rigid rod with a 12 ?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

60 degree = pi/3 rad = 1.05 rad

alpha = 2theta/t^2

apha = 1.44 x 10^7 rad/s^2

I = by rod + by sac

I = mL^2/3 + mL^2

I = 1.6 x 10^-11 kg.m^2

t = I*alpha

t = 2.304 x 10^-4 N.m

part b )

wf = alpha*t

wf = 3.8 x 10^3 rad/s

linear speed

v = wf*L

v = 3.89 m/s

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.