Iwill give the brainiest to whoever !
1. a force acting on an object does no work if
a. a machine is used to move the object
b. the force is not in the direction of the objects motion
c. the force is greater than the friction of motion
d. the object accelerates

2. a 120-meter long ski lift carries skiers from a station at the foot of a slope to a second station 40 m above. what is is the ima (ideal mechanical advantage) of the lift?
a.0.3
b.3
c. 40
d. 160

3. a mechanical device requires 420 j of work to do 230 j of work in lifting a crate. what is the efficiency of the device?
a. 0.5%
b. 190%
c. 55%
d. 183%

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:

where’s the list ? the question is incomplete

i do.

explanation:

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