#Grim reaper scythe blade pattern full#

ScytheвЂ¦1sвЂ¦scytheвЂ¦1sвЂ¦scytheвЂ¦1sвЂ¦.scytheвЂ¦1sвЂ¦.scytheвЂ¦longer break, gasping for air, sharpen the scythe. I pause a few seconds before the next вЂ“ say 10s вЂ“ on average. I feel exhausted after half an hour of scything. So they would pay us for the option to scythe our grass.Д«ut before I crank down the hypothetical velocity again, I calculate the energy demand per half an hour: If scything were that вЂefficientвЂ™ I would put into practice what we always joke about: Offer outdoor management trainings to stressed out IT managers who want to connect with their true selves again through hard work and/or work-out most efficiently. That sounds way too much already: Googling typical energy consumptions for various activities I learn that easy work in the garden needs about 100-150kcal kilocalories per half an hour! I am assuming that this energy is just consumed (dissipated) to cut the grass the grass brings the scythe to halt, and it is decelerated to 0m/s again.ДЎ kilocalorie is 4,18kJ, so this amounts to about 133kcal (!!) I use only SI units, so the resulting energy is in Joule:Д®nergy needed for acceleration: 5kg * (471m/s) 2 / 2 = 555.000J = 555kJ This would result in the following energy per arc swept. So the scythe on par with a lawn-mower would need to move at:ДўPi * (3000 rev./minute) / (60 seconds/minute) * 1,5m = 471m/s The radius is the length of the pole that I use as a simplified model.

#Grim reaper scythe blade pattern full#

Angular velocity is 2Pi вЂ“ a full circle вЂ“ times the frequency, that is revolutions per time. Velocity of a rotating body is angular velocity times radius. How fast would I have to move the scythe to achieve the same? This page says: at 3600 revolutions per minute when not under load, dropping to about 3000 when under load. How exactly the velocity has changed with time does not matter вЂ“ this is just conservation of energy.ДЇor comparison: How fast do lawn-mower blades spin? If an object with mass m is accelerated from a velocity of zero to a peak velocity v max the kinetic energy acquired is calculated from the maximum velocity: m v max 2 / 2. However, using this speed in further calculations does not make much sense:В The scythe has two handles that allow for exerting a torque вЂ“ the energy goes into acceleration of the scythe. Thus the average speed is: 2m / 0,5s = 4m/s One sweep with the scythe takes a fraction of second вЂ“ probably 0,5s. All the kinetic energy is concentrated in this вЂpoint massвЂ™.Д«ut how fast does a blade need to move in order to cut grass? Or from experience: How fast do I move the scythe?

In order to keep this simple, I assume that the weight of the scythe is a few kilos (say: 5kg) concentrated at the end of a weightless pole of 1,5m length. Yet I believe that in this case it is the acceleration required to bring the scythe to proper speed that matters so I will focus on work in terms of physics. Just holding a scythe with arms stretched out would not count as вЂworkвЂ™. So I was curious if Grim Reaper the Physicist can express this level of exhaustion in numbers. It is utterly exhausting вЂ“ there is no other outdoor activity in summer that leaves me with the feeling of really having achieved something! Yes, we tried the alternatives including a reel lawn-mower. I have a secondary super-villain identity.