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 0.34ms 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.

Question: How large is the "straightening torque?"

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 0.34ms 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. How large is the "straightening torque?

Explanation / Answer

s = 0.5at^2

alpha = (pi/3)*2/(0.34*10^-3)^2

= 18.117604 *10^6 rad/sec^2

now torque = I*alpha

If mass ias 8*10^-9 kg

I = mR^2/3 + mR^2

8*10^-9*1*10^-6(1/3+1)

10.667*10^-15

torque = 10.667*10^-15*18.117604 *10^6

= 1.9326* 10^-7 Nm

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