Part A How large is the \"straightening torque\"? if you get 4.12 as your answer

Question

Part A

How large is the "straightening torque"?

if you get 4.12 as your answer it is wrong.

The bunchberry flower has the fastest-moving parts ever observed in a plant. Initially, the stamens ar 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 0.26 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, 10 Aug rigid rod with a 10 Aug anther sac at the end. Although oversimplifying, we assume a constant angular acceleration. (Figure 1) Figure 1 v of 1 Pollen Pollen Anther sac 1.0 mm Stamen Initial configuration Final configuration

Explanation / Answer

OK, I'll give this a shot. I am going to ASSUME that:

length of rod = 1.00 mm = 0.001 meter

mass of rod = 9.00 mg = 9x10^-9 kg

mass of pod = 9.00 mg = 9x10^-9 kg

time = 0.26 milliseconds = 0.00026 seconds

Then...

angular displacement = 60 degrees = 1.0472 radians

angular acc = 2 * displacement / time^2 = 2*1.0472 / 0.00026^2 = 3.098x10^7 kg-m^2/sec

moment of inertia = (1/3) m L^2 + mL^2 =

= (4/3) * 9x10^-9 * .001^2 = 12 x 10^-12

torque = inerta * angular acc = 12 x 10^-12 * 3.098x10^7 =

= 0.00037176 N-m

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