5. An 80 kg gymnast dismounts from a high bar. He starts the dismount at full extension, then tucks to complete a number of revolutions before landing. His moment of inertia when fully extended can be approximated as a rod of length 1.8 m and when in the tuck a rod of half that length. If his rotation rate at full extension is 1.0 rev/s and he enters the tuck when his center of mass is at 3.0 m height moving horizontally to the floor, how many revolutions can he execute if he comes out of the tuck at 1.8 m height?

5. An 80 kg gymnast dismounts from a high bar. He starts the dismount at full extension, then tucks to complete a number of revolutions before landing. His moment of inertia when fully extended can be approximated as a rod of length 1.8 m and when in the tuck a rod of half that length. If his rotation rate at full extension is 1.0 rev/s and he enters the tuck when his center of mass is at 3.0 m height moving horizontally to the floor, how many revolutions can he execute if he comes out of the tuck at 1.8 m height?

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Concept explainers

Axial Load

When a bar of the uniform cross-section is acted by a load, such that the load acts along the longitudinal axis of the bar, such kinds of loadings are known as axial loadings. In general terms, a load is an external force acting on a component. An axial load acts perpendicular to the geometric cross-section of the component. Based on the direction of the application of the load, an axial load can be tensile or compressive. The analysis of bodies under the action of axial loads is generally studied under the branch of mechanics, known as statics.

Question

5. An 80 kg gymnast dismounts from a high bar. He starts the dismount at full extension, then
tucks to complete a number of revolutions before landing. His moment of inertia when fully
extended can be approximated as a rod of length 1.8 m and when in the tuck a rod of half that
length. If his rotation rate at full extension is 1.0 rev/s and he enters the tuck when his center of
mass is at 3.0 m height moving horizontally to the floor, how many revolutions can he execute if
he comes out of the tuck at 1.8 m height?
High bar
1.8 m
3 m
ANS.
Moment of inertia at full extension, I = 21.6 kg-m^2
Moment of inertia at the tuck I' = 5.4 kg-m^2
Angular velocity at the tuck = 4 rev/sec
Time interval in the tuck = 0.5 sec
i.e. In 0.5 s, he will be able to execute two revolutions at 4.0 rev/s.

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