Amachine part has the shape of a solid uniform sphere of mass 250 g and a diameter of 4.30 cm. it is spinning about a frictionless axle through its center, but at one point on its equator it is scraping against metal, resulting in a friction force of 0.0200 n at that point.

part (a):

find its angular acceleration. let the direction the sphere is spinning be the positive sense of rotation.

part (b):
how long will it take to decrease its rotational speed by 21.0 rad/s?

a) α = 9.30 rad / s²  and b) t = 2.26 s

Explanation:

Part A

For this exercise we will use the equation of Newton's second law rotational

     Σ τ = I α

     fr r = I α

Where I is the moment of inertia of the sphere

     I = 2/5 M r²

We replace

    fr r = 2/5 M r² α

    α = 5/2 fr / M r

Let's calculate

    M = 250 g (1 kg / 1000g) = 0.250 kg

    r = d / 2 = 4.30 / 2

    r = 2.15 cm (1m / 100cm) = 0.0215 m

    α = 5/2 0.0200 / (0.250 0.0215)

    α = 9.30 rad / s²

Part B

Let's use the angular kinematic equation

    w = w₀ - α t

    t = (w - w₀) / α

They give us the change in angular velocity 21.0 ras / s

    t = 21.0 / 9.30

    t = 2.26 s

nec chapter 5 contains

c. information on special occupancy areas

nec chapter 6 covers

a. special equipment

which of the following rules contain the words shall or shall not and must be adhered to?

b. mandatory rules

which of the following rules identify actions that are allowed but not required and typically cover options or alternative methods?

c. optional rules

which of the following serves as the introduction to the nec and provides an overview of the book?

a. nec article 90

organizations that test products for safety are

c. nrtls

the nec is published by the

a national fire protection association

the nec is divided into

b. 9 chapters

the nec provides informative annexes for

c. informational materials and examples

two terms from nec article 100 that trainees should become familiar with are

b. labeled and listed

explanation: