fengchen

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 * 1.** A log-raft was made by lashing six logs together, where each log has a diameter 0.25 m and length 1.90 m. How many children can safely afloat on the raft in sea water, if the average weight of a child is 200 N? Density of the logs is 800 kg/m3 and sea water is 1024 kg/m3.

Density of the logs (g)= 800kg/m^3 diameter=.25m average weight of a child= 200N length (L)=1.9 m
 * 1) of logs=6

Total raft volume= (# of log)(pi)((d/2)^2)(L) Professor's note : Try to complete your work
 * 2.**A cube of wood whose edge is 0.015 m is floating in a liquid (in a glass beaker) with one of its faces parallel to the liquid surface. The density of wood is 550 kg /m³, that of liquid is 1240 kg/m³. How far below the liquid surface is the bottom face of the cube?

Wood edge=0.015m or 15mm density of wood(dw)=550kg/m^3 density of liquid(dl)=1240kg/m^3

((dw/dl)* wood edge)=far below the liquid surface

week 4 01. A transverse wave of frequency 35 Hz propagates down a string. Two points 5 cm apart are out of phase by π/3

i. What is the wave length of the wave? (Hint : one full wavelength is 2π apart !) ii. At a given point, what is the phase difference (as a multiple of π ) between two ‘displacements for times 5 ms apart? i Frequency=35Hz Path difference =5 cm phase=π/3 relation between the phase and path difference is phase=(2π/λ)(path difference)

2π/(path difference/phase)=λ

ii period= 1/f=25ms

5ms=T/5 phase difference is phase difference =(2π/5)rad/s

Have you given up on wikis :( --- professor