Air resistance is a nonconservative force. it always opposes the motion of an object. an airplane flies from new york to atlanta and then returns to its point of departure. the net work done by air resistance during this round trip

a) is negative for slower speeds and positive for higher speeds

b) is positive

c) is negative

d)is zero

e) is negative for higher speeds and positive for slower speeds

c) is negative

Explanation:

As we know that work done by a force is the product of force and displacement vector.

W= F.d

F= Force

d= displacement

The work done by friction force always negative because it try to oppose the motion and act opposite to the direction of displacement.So the work done by air resistance is negative.

c) is negative

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: