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ENG1040 Engineering Dynamics

Practice Class 4

Rotational Dynamics

See Moodle for worked solutions to this practice class at the end of this week

This Practice Class seeks to further test your knowledge of rotational dynamics. This topic was covered in Lectures 7 to 11, these problems are sourced from Meriam and Krage, 7ed, Chapters 3-6

Rotational motion of a particle: Kinetics and the instantaneous radius

3/47 The small 0.6-kg block slides with a small amount of friction on the circular path of radius 3m in the vertical plane. If the speed of the block is 5 m/s as it passes point A and 4 m/s as it passes point B, determine the normal force exerted on the block by the surface at each of these two locations

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3/55 In the design of a space station to operate outside the earths gravitational field, it is desired to give the structure a rotational speed N which will simulate the effect of the earths gravity for members of the crew. If the centres of the crews quarters are to be located 12m from the axis of rotation, calculate the necessary rotational speed N of the space station in revolutions per minute.

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Rotational motion of a rigid body: Kinematics

5/17 The belt-driven pulley and attached disk are rotating with increasing angular velocity. At a certain instant the speed v of the belt is 1.5 m/s, and the total acceleration of point A is 75 m/s2. For this instant determine (a) the angular acceleration of the pulley and disk, (b) the total acceleration of point B, and (c) the acceleration of point C on the belt.

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Rotational motion of a rigid body: kinetics

6/19 The uniform 100kg log is supported by two cables and used as a battering ram. If the log is released from rest in the position shown, calculate the initial tension induced in each cable immediately after release and the corresponding angular acceleration of the cables. (Assume all dimensions are in metres)

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The following are supplementary questions. Demonstrators will be happy to assist students with these problems, but they need not be completed within the class for assessment purposes.

These additional problems are taken from Hibbeler: Engineering Mechanics: Dynamics, 12th Edition, Pearson.

Rotational motion of a particle: kinetics and the instantaneous radius

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Rotational motion of a rigid body: kinematics

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Calculation of the moment of inertia

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Rotational motion of a rigid body: kinetics

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