1.Your friend drops a meterstick and then you catch it. You repeat this 5 times,
ID: 3278262 • Letter: 1
Question
1.Your friend drops a meterstick and then you catch it. You repeat this 5 times, writing down how far the stick has fallen each time. You get 7.0 cm, 16.0 cm, 13.0 cm, 7.0 cm, and 12.0 cm. What is the deviation of the first reaction time from the average reaction time? (Take the average by first determining the times which correspond to each distance, and then averaging these times.) Answer in seconds.
2.You dissolve enough sugar in a cup of water that the water is saturated at 25o C. You then cool the water quickly to 15o C. What happens to the sugar-water solution? It immediately begins to freeze The color changes The water starts boiling off Some sugar precipitates out of the water The small amount of precipate which was at the bottom of the cup begins to dissolve
3.What is the theoretical value for the ball's average speed, again assuming that the ramp is at a 2o angle with a 2.5 m length? Answer in meters per second.
4.You have 1.0 L of water at 25o C. The water is currently fresh water with nothing disolved in it. You begin adding salt in increments of 25 grams. On the 15th increment—amounting to 375 total grams of salt added, you notice that you are no longer able to dissolve all of the salt, and none of the salt from the 16th increment seems to dissolve. You repeat this procedure, again starting with 1.0 L of fresh water, but this time at 30o C. Again, you find that on the 15th interval, not all of the salt gets dissolved, and on the 16th increment none of the salt seems to dissolve. You repeat this procedure, again starting with 1.0 L of fresh water, but this time at 35o C. Again, you find that on the 15th interval, not all of the salt gets dissolved, and on the 16th increment none of the salt seems to dissolve. What does this tell you about the solubility of salt in water? Choose all which apply.
The solubility is the same for both 25o C and 30o C and 35o C
The solubility does not depend on temperature You should repeat these three measurements with a smaller increment size, because the solubility of salt is not resolved for your chosen temperature range and mass increment size
The solubility is somewhere between 350 grams per kilogram and 375 grams per kilogram at all three temperatures
None of the above
Explanation / Answer
1. given average distances = 7 cm, 16 cm, 13 cm, 7 cm, 12 cm
now, the scale falls height h in time t, then
h = gt^2/2
t = sqroot(2h/g) [ where h is given ]
so the reaction times are, 1.171s, 1.771s, 1.59s, 1.171s, 1.534 s
average reaction time, tav = 1.4494 s
deviation from the first reaction time = 0.2784 s
2. When the saturatred solution of sugar is kept cold, the sugar starts to precipitate out of the dissolved form as by decreasing the
temperature we decrease the solubility of the sugar in water
4. water volume, V1 = 1l
temperature water, T1 = 25 C
after 375 grams, the salt does not dissolve inwater
again in futher data, its eveident that the solubility of salt has decreased while we go from smaller to higher temperatures
so the answer is None of the above
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