Magnetostatics - force on wire

[victorlee2]

Homework Statement

A segment of wire carries a current of 20 A
along the x-axis from x = −6 m to x = 0 and
then along the z axis from z = 0 to z = 7.2 m.
In this region of space, the magnetic field is
equal to 51 mT in the positive z direction.
What is the magnitude of the force on this
segment of wire?

Homework Equations

Fb= ILBsintheta

The Attempt at a Solution

Fb = ( 20 A ) (7.2m ) ( .051m )

the question asked for " the magnitude of the force on THIS SEGMENT of wire" so i thought to just plug in 7.2m but it turned out to be wrong so i added the 6m as well but it was wrong again. help =[

 

[victorlee2]

i have another question

A proton moving at 1.2 × 106 m/s through a
magnetic field of 4.3 T experiences a magnetic
force of magnitude 4.9 × 10−13 N.
The charge of proton is 1.60218 × 10−19 C
and the mass of proton is 1.67262 × 10−27 kg.
What is the angle between the proton’s
velocity and the field?
Answer in units of ◦.

Is this question simply just plugging the values into Fb = BILsintheta and solve for theta? it seems too easy to be true.