George W.
Woodruff School of Mechanical Engineering
Georgia Institute of Technology
ME3017 HW SET #4 Due Thursday 2/20/2025
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1) The circuit shown in the figure below is in steady-state with switch S open. The
switch is closed at t=0.
a. Find the capacitor voltage vo(0-) just before the switch is closed
and its steady-state value after the switch is closed assuming a
constant source voltage vs.
b. Use the node method to derive a differential equation relating
vo(t) to the source input vs(t) for t0.
c. Find vo (t) and i(t) for t0 assuming a constant sourse voltage vs
and the initial condition you found in (a).
2) Consider the circuit shown in the figure.
a. Obtain a mathematical model for the circuit using the loop method.
b. Define a suitable set of state variables and obtain the state variable model.
c. Use the method of Complex Impedances to determine the total impedance of the
circuit.
d. Determine the transfer function V0/Vs using (c) and either (a) or (b). Show that both
methods give the same result.
e. Use Matlab (or if you prefer Simulink) to numerically find and plot v0(t) and i1(t) for
0t2 in response to a square wave input vs of amplitude 5 V and frequency 10 Hz
(zero initial conditions). Assume R=50 , L=0.1 H, and C=0.001 F.
3) Text Problem 6.26 with the capacitor on the left replaced by inductor L.
4) Solve Text Problem 6.41 if the stall torque TL=1.9 N.m.
5) Consider the robot arm of Text Problem 6.42 and assume that L=0 and the moment of
inertia of the arm about the axis of rotation is Iarm.
a) Drive an expression for the effective inertia felt at the motor shaft in terms of
Ni’s, Iarm, and and IGi’s.
b) Given the numerical values specified in the problem statement find and plot the
motor input voltage, speed, current, and power profile required to produce a
sinusoidal arm motion (t)=0.1 sin t. Assume N1N2=20.