For a single degree of freedom spring-mass-damper system subjected to harmonic forcing, the part of the motion (response) that decays due to damping is known as:
In vibration problems, always separate total response into transient (dies out) and steady-state (persists). Only the transient part is affected by damping decay.
steady-state response
non-transient response
Step 1: General solution of forced vibration.
The displacement of a damped, harmonically forced system is \[ x(t) = x_{\text{transient}}(t) + x_{\text{steady}}(t). \]
Step 2: Nature of each part.
- The transient response is due to initial conditions and decays exponentially because of damping. - The steady-state response is the long-term periodic motion at the forcing frequency, which persists.
Step 3: Identification.
Since damping causes exponential decay, the response that disappears with time is the transient response.
\[\boxed{\text{Transient response}}\]
A uniform rigid bar of mass 3 kg is hinged at point F, and supported by a spring of stiffness \( k = 100 \, {N/m} \), as shown in the figure. The natural frequency of free vibration of the system is ___________ rad/s (answer in integer).
Two designs A and B, shown in the figure, are proposed for a thin-walled closed section that is expected to carry only torque. Both A and B have a semi-circular nose, and are made of the same material with a wall thickness of 1 mm. With strength as the only criterion for failure, the ratio of maximum torque that B can support to the maximum torque that A can support is _________ (rounded off to two decimal places).
A thin flat plate is subjected to the following stresses: \[ \sigma_{xx} = 160 \, {MPa}; \, \sigma_{yy} = 40 \, {MPa}; \, \tau_{xy} = 80 \, {MPa}. \] Factor of safety is defined as the ratio of the yield stress to the applied stress. The yield stress of the material under uniaxial tensile load is 250 MPa. The factor of safety for the plate assuming that material failure is governed by the von Mises criterion is _________ (rounded off to two decimal places).
A prismatic vertical column of cross-section \( a \times 0.5a \) and length \( l \) is rigidly fixed at the bottom and free at the top. A compressive force \( P \) is applied along the centroidal axis at the top surface. The Young’s modulus of the material is 200 GPa and the uniaxial yield stress is 400 MPa. If the critical value of \( P \) for yielding and for buckling of the column are equal, the value of \( \frac{l}{a} \) is __________ (rounded off to one decimal place).
A jet-powered airplane is steadily climbing at a rate of 10 m/s. The air density is 0.8 kg/m³, and the thrust force is aligned with the flight path. Using the information provided in the table below, the airplane’s thrust to weight ratio is ___________ (rounded off to one decimal place). 
F and G denote two points on a spacecraft’s orbit around a planet, as indicated in the figure. O is the center of the planet, P is the periapsis, and the angles are as indicated in the figure. If \( OF = 8000 \, {km} \), \( OG = 10000 \, {km} \), \( \theta_F = 0^\circ \), and \( \theta_G = 60^\circ \), the eccentricity of the spacecraft's orbit is __________ (rounded off to two decimal places).