Answer Happy

1. Briefly explain resonance in a few words? (1) 2. (a) Consider an aluminium disk presented in Figure 1 with density 8g/cm", thickness 20 mm and diameter 135 mm, determine its radius, (b) use your answer in (a) to calculate the moment of inertia. disk Figure 1 Aluminium disk. (3) 3. If a mass of 750 g is hung on a piece of string. Calculate its weight. When the same string is wound around a pulley with a radius of 33 cm, what would be the torque? 4. In this experiment there are three possible sources of torque on the aluminium disk. Mention two and explain each. (2) 5. Given a graph of angle (rad/s) versus time (s) in Figure 2, use it to estimate damped angular frequency and the damping constant. Also estimate the natural (undamped) angular frequency.
0.5 mm -0.5 -1 0 20 40 60 BD 100 time (seconds) Figure 2 Under critically damped harmonic oscillations. (8) 6. The un-damped system has angular frequency o = 15 Hz. The system is then damped with damping constant y = 5 Hz. At what angular frequency must the system be driven to achieve the maximum amplitude? (4) 7. Consider a system that oscillates without damping and has a certain period. Upon introducing damping, will the period get longer, shorter or stay the same? (2) 8. Differentiate between damped, un-damped oscillations. (2)