Acoil has n turns enclosing an area of a. in a physics laboratory experiment, the coil is rotated during the time interval δt from a position in which the plane of each turn is perpendicular to earth's magnetic field to one in which the plane of each turn is parallel to the field. the magnitude of earth's magnetic field at the lab location is b.
a: what is the magnitude φinitial of the magnetic flux through one turn of the coil before it is rotated?

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".