The efficiency of a screw is low because of

width

friction

length

height

The efficiency of a screw is low because of friction.

Explanation:

A screw is a simple machine that is used to convert a torque to linear force and rotational motion to linear motion. The efficiency of a screw is given by :

Where

l = pitch distance in mm

T = torque in N-m

The efficiency of screw is less because the output is less as compared to input or there is more input than output. This implies that there is more friction.

Hence, the correct option is (b) "friction".

568.98

explanation:

its math

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: