P221_2008_week2

# P221_2008_week2 - Estimate the time it takes for a free...

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Estimate the time it takes for a free fall drop from 10 meters height. Also, estimate the time a 10 m platform diver would be in the air if he takes off straight up with a vertical speed of 2 m/s (and clears the platform of course!). Please provide a brief description of how you arrived at your estimates. (A: 18 correct B 9 correct) e 10m / 9.8m/s= 1.02s (UNITS!); 10m / 2m/s= 5s (RTFQ!!) ( It would take about .98 seconds for the ball to fall to the ground. The speed of the fall is 9.8 m/s. NO!!!!!! v2=v1-g.t; 2m/s=0-[9.8,/s^2].t; t= 0.2 s (wrong eqn) ( the answer to the question for just a free fall is 2 seconds. something that is free falling, falls at an acceleration of -9.80 m/s2 velocity is -19.6 m/s NO, ONLY IF v=const. Correct answer: 1.43 sec for A, 1.65 sec for B

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Estimate the time it takes for a free fall drop from 10 meters height. Also, estimate the time a 10 m platform diver would be in the air if he takes off straight up with a vertical speed of 2 m/s (and clears the platform of course!). Please provide a brief description of how you arrived at your estimates. (A: 19 correct B 10 correct) d I found this throughusing the formula y-y0= v0t-0.5at^2. because this is a free fall a=-g which is -9.8m/s^2 y=-10m because the fall is downwards and we assume to start at zero for simplicity and the initial velocity was 0, therefore, the formula becomes -10m-0= 0t-.5(9.8m/s^2)t^2 t^2 = 10/4.9 which leads t=2.04s, and taking into account sig figs becomes 2 s. (oops SQRT missed; again carrying
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P221_2008_week2 - Estimate the time it takes for a free...

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