Power Calculations

Razi

Hello everybody

Could you help me to solve this question ?

Best regards
Razi

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HallsofIvy

Since you use the term "drag coefficient" can we assume that you know what it means? According to Wikipedia, the drag coefficient is given by $$\displaystyle c_d= \frac{2F_d}{\rho u^2A}$$ where $$\displaystyle c_d$$ is the drag coefficient, $$\displaystyle F_d$$ is the drag force, $$\displaystyle \rho$$ is the density of the fluid, u is the speed through the fluid, and A is the cross section area. You are asked for the drag force so solve for that: $$\displaystyle F_d= \frac{c_d\rho u^2A}{2}$$. You are given that A= 400 square cm. and $$\displaystyle c_d= 0.6$$. You will need to look up the density of air and water and calculate u, the speed of an object moving at 1000 rev/min around a circle of radius $$\displaystyle 10 sin(120^o)$$.

Razi

Thanks Dear HallsofIvy for your help

Best regards