Question

thought i got this, but i guess not. someone help me out here? pics to follow. can't describe...matching 3d vector plots

Answer 1

i got that F=i is simple....it's b. but i thought i had all the others right. webwork won't tell me which ones i got right and which i got wrong. really frustrating.

Answer 2

#3 F = i is same as F = 1i + 0j + 0k
it has a constant component along x direction at each point in the space

Answer 3

B is right for #3

Answer 4

#4 : F = xi + yj + zk

Notice that it is same as the position vector and the position vector points radially outwards (think of a sphere)

http://mathinsight.org/media/applet/image/large/divergent_vector_field_movable_sphere.png

Answer 5

C is clearly wrong for #4 as C is rotate in xy plane instead of shooting radially outward from origin

Answer 6

C is clearly wrong for #4 as the vector field in C is rotating in xy plane instead of shooting radially outward from origin

Answer 7

oh, if that's a sphere, then it'll be A or E. i can't tell a difference between A and B.

Answer 8

er. between A and E.

Answer 9

Exactly! but it cannot be A because the vectors in A don't have a z component

Answer 10

? : 1
? : 2
`B : 3`
`E : 4`
? : 5
? : 6

Answer 11

lets look at 5

Answer 12

5 would be A then.

Answer 13

#5 : xi + yj + 0k

it has to be A because thats the only field without z components and with vectors pointing radially outward in xy plane

Answer 14

? : 1
? : 2
`B : 3`
`E : 4`
`A : 5`
? : 6

Answer 15

6 is gonna be D because the y is negative.

Answer 16

nope. 6 also has no z component

Answer 17

the field rotates in xy plane only

Answer 18

it's really hard to see in these pictures if there's a Z or not. lol

Answer 19

how about

? : 1
? : 2
`B : 3`
`E : 4`
`A : 5`
`F : 6`

Answer 20

ok, i think 1 is D cause there's a Z and 2 is C cause there is no Z?

Answer 21

`D : 1`
`C : 2`
`B : 3`
`E : 4`
`A : 5`
`F : 6`

Answer 22

yes try that

Answer 23

YES! correct. ok, it was just really hard for me to see which had z components and which didn't. on to the next section later today. line integrals which should be fairly easy. i'm good at integrals.

Answer 24

line integrals are fun, if u look at the given vector fields, only two are rotating.
all others are just spreading out

Answer 25

have u noticed that ?

Answer 26

yeah. i see why.

Answer 27

C and F are rotating forming whirlpool like field around origin in xy plane

Answer 28

and if u look at the equations, only two have components whose x an y components are switched : `-yi + xj`

Answer 29

`-yi + xj` is perpendicular to the position vector `xi + yj`

Answer 30

the force `-yi + xj` at that position would be :