A wire carries a current of 6.91 A in a direction that makes an angle of 19◦ with the direction of a magnetic field of strength 0.289 T. Find the magnetic force on a 6.7 m length of the wire. Answer in units of N.

4.454 N.

Explanation:

The force on a current carrying conductor in a magnetic field is given as,

F = BILsinФ Equation 1

Where F = magnetic Force, B = magnetic Field, I = current, L = Length of the wire, Ф = The angle between the conductor and the Field.

Given: B = 0.289 T, I = 6.91 A, L = 6.7 m, Ф = 19°

Substitute into equation 1

F = 0.289(6.91)(6.7)sin19

F = 0.289×6.91×6.7×0.33

F = 4.454 N.

Hence the magnetic force = 4.454 N.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s

d. platinum would have the greatest temperature increase because it has the lowest specific heat.