A reasonable estimate of the moment of inertia of an ice skater spinning with her arms at her sides can be made by modeling most of her body as a uniform cylinder. Suppose the skater has a mass of 64 kg. One-eighth of that mass is in her arms, which are 60 cm long and 20 cm from the vertical axis about which she rotates. The rest of her mass is approximately in the form of a 20-cm-radius cylinder. a. Estimate the skater’s moment of inertia to two significant figures. b. If she were to hold her arms outward, rather than at her sides, would her moment of inertia increase, decrease, or remain unchanged? Explain.
A reasonable estimate of the moment of inertia of an ice skater spinning with her arms at her sides can be made by modeling most of her body as a uniform cylinder. Suppose the skater has a mass of 64 kg. One-eighth of that mass is in her arms, which are 60 cm long and 20 cm from the vertical axis about which she rotates. The rest of her mass is approximately in the form of a 20-cm-radius cylinder. a. Estimate the skater’s moment of inertia to two significant figures. b. If she were to hold her arms outward, rather than at her sides, would her moment of inertia increase, decrease, or remain unchanged? Explain.
A reasonable estimate of the moment of inertia of an ice skater spinning with her arms at her sides can be made by modeling most of her body as a uniform cylinder. Suppose the skater has a mass of 64 kg. One-eighth of that mass is in her arms, which are 60 cm long and 20 cm from the vertical axis about which she rotates. The rest of her mass is approximately in the form of a 20-cm-radius cylinder.
a. Estimate the skater’s moment of inertia to two significant figures.
b. If she were to hold her arms outward, rather than at her sides, would her moment of inertia increase, decrease, or remain unchanged? Explain.
The figure gives the acceleration a versus time t for a particle moving along an x axis. The a-axis scale is set by as = 12.0 m/s². At t = -2.0
s, the particle's velocity is 11.0 m/s. What is its velocity at t = 6.0 s?
a (m/s²)
as
-2
0
2
t(s)
4
Two solid cylindrical rods AB and BC are welded together at B and loaded as shown. Knowing that the average normal stress must not
exceed 150 MPa in either rod, determine the smallest allowable values of the diameters d₁ and d2. Take P= 85 kN.
P
125 kN
B
125 kN
C
0.9 m
1.2 m
The smallest allowable value of the diameter d₁ is
The smallest allowable value of the diameter d₂ is
mm.
mm.
Westros, from Game of Thrones, has an area of approximately 6.73⋅106 miles26.73⋅106miles2. Convert the area of Westros to km2 where 1.00 mile = 1.609 km.
Chapter 7 Solutions
College Physics: A Strategic Approach (3rd Edition)
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