The 20-kg roll of paper has a radius of gyration ka = 120 mm about an axis passing through point a. it is pin supported at both ends by two brackets ab. the roll rests on the floor, for which the coefficient of kinetic friction is μk = 0.2. if a horizontal force f = 60 n is applied to the end of the paper, determine the initial angular acceleration of the roll as the paper unrolls.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

no. dot product   =0 when vecs at right angles

the higher the current the higher the mag field around it the higher the influence on the compass