11. A 160-lb man carries a 25-lb can of paint up helical staircase that encircle

ID: 2842080 • Letter: 1

Question

11. A 160-lb man carries a 25-lb can of paint up helical staircase that encircles a silo with

a radius of 20 ft. If the silo is 90 ft high and the man makes exactly three complete

revolution. How much work is done by the man against gravity in climbing to the top?

14. An object moves in the force eld F = y2i+2(x+1)yj counterclockwise from the point

(2; 0) along the elliptical path x2+4y2 = 4 to (??2; 0) and back to the point (2; 0) along

the x-axis. How much work done by the force eld on the object?

13. Determine whether or not F is a conserviative vector eld. If it is, nd the potential

function.

F =< ye^2 + sin y; e^x + x cos y >

Work = Force* Displacement*Cos(tetha)

on the first his displacement was 90ft and the force was 160lbs+25lbs *Cos (3*2pi)

so 16650 foot lbs

2nd displacement was zero, so zero work was done.

Vector field is conservative if the x and y components derivatives are equal.

partial of (ye^2+siny)dx ---> 0

partial of (e^x+xcosy) dy ---> -xsiny

those are not equal therefore not conservative.

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