Astudent places a magnetic compass near an insulated copper wire with electric current moving through it. he notices that the compass needle no longer points north.
which of the following best explains this observation?
a. the magnetic poles that determine north and south reverse periodically.
b. the insulation prevents the compass from detecting earth's magnetic field.
c. the compass detects the magnetic field produced by the electric current.
d. the copper wire exerts an electrostatic force on the compass needle.

Why does the input force have to be greater than the force needed to lift the bale?

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 710 n/m. it is initially at rest on an inclined plane that is at an angle of θ = 23° with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is μk = 0.19. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. a) what is the block's initial mechanical energy? b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.

The transfer of heat through the movement of a gas or liquid a. convection b. conduction c. radiation