Which statement correctly describes the differences between positive and negative acceleration? positive acceleration describes a change in speed; negative acceleration describes no change in speed. positive acceleration describes no change in speed; negative acceleration describes a change in speed. positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed. positive acceleration describes a decrease in speed; negative acceleration describes an increase in speed.

Positive acceleration describes an increase in speed; negative acceleration describes a decrease in speed.

Explanation:

Acceleration is defined as:

where

v is the final velocity

u is the initial velocity

is the time taken for the change in velocity to occur

The value of is always positive, so the sign of the acceleration depends on the numerator. More specifically, we have two situations:

- if , then it means that the final velocity is greater than the initial velocity, so the acceleration is positive and the speed is increasing

- if , then it means that the final velocity is smaller than the initial velocity, so the acceleration is negative and the speed is decreasing

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: