A 4.0 m long thin rod is pinned so that it spins about its center. The rod has a rotational inertia of 8.0 kg m2 about this center. The rod has two 3.0 kg masses attached at each end. What force F must be applied to one end to make the system rotate with an angular acceleration of 4.0 rad/s2 about its center

they should be similar or the same

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.