Recent content by YanZhen

wow,thanks for your wonderful answer,it solved my question.and it also requires a point of knowlege about vectors.(x1,y1)X(x2,y2)=x1y2-y1x2

i,j,k arevector I know L=P*r=m*v*r=m(acosωti+bsinωtj)*(-aωsinωti+bωcosωtj)=mabw((cos^2)ωt+(sin^2)ωt)k=mabωk. but why m(acosωti+bsinωtj)*(-aωsinωti+bωcosωtj)=mabw((cos^2)ωt+(sin^2)ωt)k.I need some detail. please help me.

yes

then,either the question or the answer is wrong.

emmm.i can't open it. could you send me the content?thank you:biggrin:

so,how should we describe the relationship between V and E? i'm so out of ideas.

hei sir.i'm sorry to say maybe the book is right. maybe firework with an initial velocity of 25.0 m/s at 30.0° with respect to the horizontal. and it was calculated that the answer is 25.4

C=Q/V C is a constant E=F/q=((kQq)/(d^2))/q=kQ/(d^2)=kCV/(d^2) is this the answer you want?

E=U/d d is a constant so Ea=2E Eb=4E and U is like mgh,E is like g.one in the electric field,one in the force field. understand?

Do you have original question? Why U=(1/2)QV and U=(1/2)Q^2V? (1/2)QV≠(1/2)Q^2V.I can't understand it. Could you explain it?