Question

Magnetic Force Problem: Did I solve this problem correctly?

Answer 1

A proton moves in the magnetic field B = 0.50 i T with a density of 2.1 * 10 m
speed of 1.0 * 107 m/s in the directions shown in FIGURE EX32.26. For each, what is magnetic force Fu on the proton? Give your answers in component form.

Answer 2

I get that \[F= q V x B = (1.60 x 10^{-19})(1.0x10^7)(0.50)\sin270 \]

Answer 3

and using the right hand rule, I get that the force points towards the z axis?

Answer 4

upwards

Answer 5

@IrishBoy123

Answer 6

If the force is along the z-axis and it's upwards, should it not be positive?

sin(270^o)=-1, so that value gives a force downwards, why not just sin(90^o)?

Answer 7

I just realized that theta is actually 90 degrees lol

Answer 8

lol yeah, i think that should be right

Answer 9

:D

Answer 10

Hey, I have another question.

Answer 11

When calculating the magnetism force, does the sign of the charge matter?

Answer 12

"However, though q is a scalar quantity, it can affect the direction of the force vector. If q has a negative value, then has a negative value, and so the force vector will point in a direction opposite from what the right-hand rule might tell you."

http://www.sparknotes.com/testprep/books/sat2/physics/chapter15section2.rhtml

Answer 13

Ohhh ok :) thanks

Answer 14

this time, it's an electron

Answer 15

RHR tells me force points in the j direction?

Answer 16

no problem, soo the force would be the opposing side of the RHR, it would be in the -y direction

Answer 17

wait hold on a minute, i might be wrong

Answer 18

The answer key says it's just positive J direction

Answer 19

i think it should be into the page (-y) still, because the charge is negative

Answer 20

F= -8.0x10^-13

Answer 21

Oh, we don't need to put the negative sign right, it's just supposed to change the direction given by RHR?

Answer 22

Can you try the RHR? I think I'm not doing it properly lol

Answer 23

i think you need the sign because it's related to the coordinate system and it gives direction to the vector.

Answer 24

Sure, i usually do this with my index and my thumb.

make the index be the velocity vector and your thumb the magnetic field vector.

At this point, a positive force experiences a force towards the back of your hand and a negative towards the palm of your hand.

Answer 25

So for the 2nd image, if you do the RHR, you notice your index points down and your thumb to the side, so the force should be towards your palm which is -y