What is the meaning of "below horizontal axis" on a position vs. time graph

•Any point below the t = axis means that the object is in the opposite direction than when the line was above the axis. ... (horizontal) Each point on the time axis has a positive speed, which means that the object is moving forward.

•In a position-time diagram, the speed of a moving object is indicated by the slope or slope of the diagram line. If the line in the graph is horizontal, then the line after time = 5 seconds in graph 2 in the following figure, so the slope is 0, as is the speed. Object position does not change

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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: