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Find the work done by the given vector fieldFF along the specified curve C.

F(x,y)=yi-xjwhere Cis the portion of the circle of radius 2, centered at the origin, and in the first quadrant, traversed counterclockwise from2,0-0,2.

Short Answer

Expert verified

The required work done isCF(x,y)dr=-2.

Step by step solution

01

Given Information

The vector field is F(x,y)=yi-xj

Curve is portion of circle of radius 2, centered at origin in first quadrant, traversed counterclockwise from2,0-0,2

02

Parametrization of curve

The curve is parametrized as

r(t)=cost,sintfor0t2

r'(t)=ddtr(t)

=ddtcost,sint

=-sint,cost

03

Rewrite the vector field

It can be written as

F(x,y)=yi-xj

F(x(t),y(t))=sinti-costj

=sint,-cost

04

Calculating Work done

The required integral is CF(x,y)dr

=CF(x(t),y(t))r'(t)dt

=0/2sint,-cost-sint,costdt

=0/2[(sint)(-sint)+(-cost)(cost)]dt

Applying values

=0/2-sin2t-cos2tdt

=0/2-sin2t+cos2tdt

=0/2(-1)dt

=-1[t]0/2

=-12-0

=-2

Hence, work done isCF(x,y)dr=-2

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