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 One: How large is the "straightening torque?"

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

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

Explanation / Answer

the torque is

T = (1/2)mv^2

where m = 8.0 mg = 8.0 x 10^-3 kg and v = r x w

where r = 1.0 mm = 1.0 x 10^-3 m and w = (theta/t),theta = 60o = (pi/3) radians and t = 0.34 ms = 0.34 x 10^-3 s

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