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

a high pressure system is a dense air mass that is usually cooler and drier than the surrounding air. a low pressure system is a less dense air mass that is usually wetter and warmer than the surrounding air.

in general, areas that experience high atmospheric pressure also experience fair weather. low pressure systems can cause the formation of clouds and storms. air usually flows from areas of high pressure to areas of low pressure..