In order to decrease the friction an object experiences, you can either change
the surface it sits on or you weight.

Reduce its weight

Explanation:

For an object on a flat surface, the maximum force of friction experienced by the object is given by:

where

is the coefficient of friction

W is the weight of the object

As we can see from the formula, there are two ways of reducing the  friction:

- Decreasing --> this coefficient depends on the material and on the roughness of the surface, so this can be changed by changing the properties of the surface

- Decreasing W, the weight --> this can be done by reducing the mass of the object

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:

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2