Why does the ball rolling westward appear to move east when observed from the outside of the truck

Because the truck is moving to the east faster than the ball is moving west.

Explanation:

In this problem the text reads:

Ball                                          Truck

Rolling west at 0.25 m/sMoving east at 1.0 m/s

You get asked if the observer in the truck would see the ball moving to the west, the answer is yes, cause the observer in the truck would be moving to the east along with the truck, but someone looking at the ball from the outside will see the ball moving east because the speed of the ball is less than that of the truck.

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:

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.