A uniform spherical shell of mass 8.90 kg with diameter 51.0 cm has four small m

Question

A uniform spherical shell of mass 8.90 kg with diameter 51.0 cm has four small masses of mass 2.50 kgattached to its outer surface and equally spaced around it. This combination is spinning about an axis running through the center of the sphere and two of the small masses (Figure 1) .

Part A

What friction torque is needed to reduce its angular speed from 74.0 rpm to 54.0 rpm in a time interval of 28.0 s ?

SubmitMy AnswersGive Up

Incorrect; Try Again; 4 attempts remaining

Provide FeedbackContinue

Figure 1 of 1

A uniform spherical shell of mass 8.90 kg with diameter 51.0 cm has four small masses of mass 2.50 kgattached to its outer surface and equally spaced around it. This combination is spinning about an axis running through the center of the sphere and two of the small masses (Figure 1) .

Part A

What friction torque is needed to reduce its angular speed from 74.0 rpm to 54.0 rpm in a time interval of 28.0 s ?

SubmitMy AnswersGive Up

Incorrect; Try Again; 4 attempts remaining

Provide FeedbackContinue

Figure 1 of 1

Explanation / Answer

I_shell = (2/3)mr² = (2/3) * 8.9kg * (0.255m)² = 0.386 kg·m²
total I = 0.386kg·m² + 4 * 2.5kg * (0.255m)² = 1.036 kg·m²

= / t = (74 - 54)rev/min * 2rad/rev * 1min/60s / 28s
= 0.0748 rad/s²

required torque = I = 1.036kg·m² * 0.0748rad/s² = 0.077 N·m


Hope this helps!

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.