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 degree angle in just 0.31ms 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, 10ug rigid rod with a 10ug anther sac at the end. Although oversimplifying, we'll assume a constant angular acceleration.(Figure 1)

Part A

How large is the "straightening torque"?

Express your answer to two significant figures and include the appropriate units.

Part B

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

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

s = 0.5at^2

alpha = (pi/3)*2/(0.31*10^-3)^2

= 21.793913 *10^6 rad/sec^2

now torque = I*alpha

If mass ias 10*10^-9 kg

I = mR^2/3 + mR^2

10*10^-9*1*10^-6(1/3+1)

13.3333*10^-15

torque = 13.3333*10^-15*21.793913 *10^6

= 2.906* 10^-7 Nm

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