Assignment:
Answer all questions on this paper.
1. What is the minimum number of 1/2 cm expansion joints that must be put in a 100-m wall made of sheets of plasterboard in order to prevent buckling if the temperature can range from -5° C to 40° C?
(Plasterboard has a coefficient of linear expansion, a = 5 x 10-6K-1)
2. A 12-k mass on a s nn:. under oes SHM with a eriod of 1.6 s. Its amplitude is 5.0 cm. Draw a sketch of the situation, list knowns and unknowns, and then find the spring constant, k.
3. Explain, using the atomic model of matter,
(a) Why hot air rises from the baseboard heating mit in a room.
(b) Why cold air sinks to the bottom of a refrigerator.
4. At stretched string is 4.5 m long vibrates in a standing wave pattern with 9 loops. The vibrating string has a frequency f = 360 Hz. Draw a sketch of the situation then answer the questions.
5. A piano note of unknown frequency, f, and a tuning fork with f = 384 Hz are both sounded at the same time. Beats are heard. The frequency of the beats, fbeat = 4 HZ. When the same piano key is played at the same time as a tuning fork with frequency 395 Hz, the beat frequency is 7 Hz. What is the frequency of the piano note?
6. Two pots are identical except that the flat bottom of one is aluminum, whereas that of the other is steel. Water in these pots is boiling away at 100.0°C at the same rate. The temperature of the heating element on which the aluminum bottom is sitting is 180.0°C. Assume that heat enters the water only through the bottoms of the pots and find the temperature of the heating element on which the copper bottom rests.