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Unformatted text preview: following page) 881-181 – 15 – N01/430/S(3) (Question D1 continued) The diagram below shows typical audiograms for people aged 40 and 65, whose loss of hearing is due only to ageing. Hearing loss / dB 0 -20 40 year old -40 65 year old -60 -80 250 500 1000 2000 4000 8000 Frequency / Hz (d) Use the information in the diagram to describe the changes in hearing that take place due to ageing. [2] ......................................................................... ......................................................................... ......................................................................... (e) For a 65 year old person, what is the sound intensity in W m −2 that is just audible at a frequency of 2000 Hz? [3] ......................................................................... ......................................................................... ......................................................................... ......................................................................... ......................................................................... (f) Should a hearing aid for a 65 year old amplify all frequencies equally? Explain your answer. [2] ......................................................................... ......................................................................... ......................................................................... 881-181 Turn over – 16 – N01/430/S(3) D2. When a person lifts a suitcase, the spine experiences large extra forces. In a simplified model of the situation, the spine can be treated as a rigid rod. In this model, when the suitcase is lifted, three extra forces act on the spine which need to be in equilibrium. ! The additional force due to lifting the suitcase, S. ! The additional force from the muscles, F. ! The additional force on the base of the spine, R. The diagram below shows the directions and points of action of S and F, but not R. –– –– –– — – — — — – –– — — — –– –– 0. 5 —— — — —— —— —— o 70 –– –– base of spine — — –– –– o 10— — — –– –– F — –– –– m 1. 0 m 0. 8 S m – (a) State the two conditions for S, F, and R to be in equilibrium. [2] ......................................................................... ......................................................................... ......................................................................... (b) Add an arrow to the diagram to show the approximate direction of R, the additional force on the base of the spine. [2] (This question continues on the following page) 881-181 – 17 – N01/430/S(3) (Question D2 continued) (c) Write down an expression for the torque about the base of the spine due to the force S. [2] ......................................................................... ......................................................................... ......................................................................... (d) Show that the force F is approximately nine times the force S, i.e. the muscle force is nine times the weight of the suitcase being lifted. [2] ......................................................................... ......................................................................... ...............................
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This note was uploaded on 09/30/2011 for the course CHEM 102 taught by Professor Tina during the Spring '11 term at Global.

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