Recent content by quantum_enhan

Thank you. Do you have any suggestions as to how one would approach the same problem, but going the other way? For example, evaluate: \sum ^{n}_{k=m+1} k^2. Thanks for your help

I guess I am confused as to why they randomly changed the lower limit from k=1+m to k=1, and how they did it

n^2-m^2. However, let's say you only have this term \sum ^{n}_{k=m+1} k^2 , how would you know to simplify it to n^2-m^2?

Homework Statement Can someone please explain the following for me? \sum ^{n}_{k=m+1} k^2 = \sum ^{n}_{k=1} k^2 - \sum ^{m}_{k=1} k^2 The Attempt at a Solution I have not done math in a long time, and for some reason this has me baffled. My textbook randomly does it, and does not...

I don't see how you can get tan(θ/2) from sinθ(secθ - 1). Don't you need (1-cosθ)/sinθ. I can't seem to get it to equal the half angle identity..

Homework Statement The Attempt at a Solution 2Fsin(theta)=45 N Where F=ks=(75N/m)(s-1.2m). Looking at the triangle, we can state that s, the stretched length is equal to 1.2m/cos(theta). Therefore, 2(75N/m)[(1.2m/cos(theta))-1.2m]sin(theta)=45 N...

Homework Statement The Attempt at a Solution I'm not entirely sure how to go about this question, and what to do with the maximum force that each cord can withstand. I tried setting up an equation, then taking a derivative to solve it for the maximum, but I bet there is an easier way...

sorry, x=1.2/costheta

Ok. Find theta. 2sintheta(75)(x-1.2)=45, where x=1.2costheta

The Attempt at a Solution I'm attempting to solve a question with a few unknowns, and I managed to get it to the following form: tanx(1-cosx)=0.25 I just can't seem to simplify it further and thus solve.. Any ideas?

Homework Statement A vertical force P=10 N is applied to the ends of the 0.2 m cord AB and spring AC. If the spring has an unstretched length of 0.2 m. determine the angle theta for equilibrium. Take k = 150 N/m. Homework Equations Fspring=ks Fy=0 Fx=0 The Attempt at a Solution...

nobody?

Homework Equations v=d/t The Attempt at a Solution VL=VR+2km/h d=6km tL1tR+4min tL2=tR +2 VL= 6km / (2-4) = 3km/min which is OBVIOUSLY WRONG. I have tried numerous things for the past couple hours, but can't seem to figure it out/. Help?