Which of the followijg is an example of kinetic energy A. A boy resting on a park bench
B. A book sitting on a shelf
C. A rubber band stretched as far as it can go
D. A swing moving back and forth​

D

Explanation:

D. A swing moving back and forth

Explanation:

The answer to ur question is option D) A swing moving back n forth bcos kinetic energy is energy that is due to motioneven tho option C) states that the rubberband is stretched, it is still considered a potential enrgy bcos it is in a position that wud change from potential to kinetic energysp the correct ans iz option D)

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:

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered