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A) The density of an irregularly shaped object was determined as follows. The ma

ID: 884272 • Letter: A

Question

A) The density of an irregularly shaped object was determined as follows. The mass of the object was found to be 28.90 g ± 0.03 g. A graduated cylinder was partially filled with water. The reading of the level of the water was 5.5 cm3 ± 0.1 cm3. The object was dropped in the cylinder, and the level of the water rose to 9.8 cm3 ± 0.1 cm3 . What is the density of the object with appropriate error limits?

B) A column of liquid is found to expand linearly on heating. Assume the column rises 5.25 cm for a 10.0oF rise in temperature. If the initial temperature of the liquid is 99.7oF, what will the final temperature be in oC if the liquid has expanded by 19.5 cm?

C) A parsec is an astronomical unit of distance where 1 parsec = 3.26 light years (1 light year equals the distance traveled by light in one year). If the speed of light is 186,000 mi/s, calculate the distance in meters of an object that travels 3.0 parsecs.

D) Lipitor, a pharmaceutical drug that has been shown to lower "bad" cholesterol levels while raising "good" cholesterol levels in patients taking the drug, had over $11 billion in sales in 2006. Assuming one 1.0-g pill contains 6.5% of the active ingredient by mass, what mass in kg of active ingredient is present in one bottle of 50 pills?

Explanation / Answer

A)
m = 28.90 g ± 0.03 g
Vi= 5.5 cm3 ± 0.1 cm3.
Vf = 9.8 cm3 ± 0.1 cm3

Volume of object = Vf-Vi
    = (9.8 cm3 ± 0.1 cm3) - (5.5 cm3 ± 0.1 cm3)
    = (9.8-5.5)cm3 ± (0.1+0.1) cm3
    = 4.3 cm3 ± 0.2 cm3

density =mass / volume
            = 28.9 / 4.3
             = 24.6 g/cm3

To find error in density use:
error in density / density = error in mass / mass + Error in volume/volume
error in density / 24.6 = 0.03/28.9 + 0.2/4.3
error in density = 1.17

so density = 24.6 g/cm3   ± 1.17   g/cm3

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