Recent content by Heather

ZrO2 is an ionic conductor used in automobile engine control systems. At 800oC the mobility of Zr4+ is 0.01m2/V.sec, and of O2- it is 0.04 m2/V.sec., there are 4.5 x 1017 mobile Zr4+ ions/m3, and 2.0 x 1018 mobile O2- ions/m3. What is the conductivity of ZrO2 at this temperature, in S.m-1...

yes! thank you so much for helping me through that problem, and for being so patient.

The average velocity vector would be v=-(4r/π)i+(4r/π)j

#3 Position= r(0)i+r(1)j for final, and Position=r(1)i+r(0)j for initial #4 ||v||=√((-1r/(π/4))2+(1r/(π/4))2) --> (4 √(2) √(r2))/pi

Is 0.7458 correct? #1 at t=0, x=r and y=0 #2 at t=pi/4, x=rcos(2pi/4) and y=rsin(2pi/4) #3 Displacement at x=rcos(2pi/4)-x(or r) and y=rsin (2pi/4) - 0 #4 The average vector velocity is the (final position - initial position) dived by the (final time - initial time).

ahh duh, ok so then it should look something like this, taking the root of the sum of the x and y coordinates for t=π/4 and the root of the sum of the x and y coordinates at t=0 subtract the final position from the initial, and divide by two. Giving (2-root2)/2.

At t=0 y=0 and x=r At t=π/4 I an uncertain because I haven't been able to figure at what r is. I guess my real problem isn't finding the average but figuring out what r is.

Homework Statement Calculate the average vector velocity between 0 and pi/4 sec. Homework Equations x=rcos2t y=rsin2t Vx=2rsin(2t) Vy=2rcos2t Ax=4rcos(2t) Ay=-4cos(2t) Circular path is x^2+y^2+r^2 The Attempt at a Solution I'm not sure if I am missing something simple or not, What I need to...