The professor gave us no background material or explanations for any of these questions.
1. Imagine that molecules of H20 are stacked up in a cubic array, like a large number of cubical boxes. Each water molecule is taken to be at the center of each cube in this array. Let the side of each cube be L. Given that the density of water is I g/cm3, estimate the dis tance L. You are given that 18 gms of water contains 6.02 x 1024 molecules.
A. 6 angstroms
B. 1.44 x 10-8 cm
C. 14.4 angstroms
D. 3.0 x 10-10 m
Until this point I had never heard of/read about angstroms so I have no idea.
2.A student wishes to make a measurement of the road distance from his dormitory to the physics building of his university. she uses her car's trip odometer, which measures distance only in units of a tenth of a mile. She makes one trip, and the odometer reads 0.3 mi. What can she say is the distance ?
A. 3
B. 2
C. 1
D. 0
I put A, but that seems too simple. And the question is poorly written (he/she).
3. In the above problem to how many significant figures can she claim she knows the distance?
A. 3
B. 2
C. 1
D. 0
I put C.
4. In the same problem above if she has to know the distance to the physics department to the next significant figure how many round trips to the department should she take ?
A. 100
B. 10
C. 5
D. 3
None of these seem right to me. I wonder if the question should not read "round trips".
Thanks a lot!
It didn't let me finish writing this.
For number 1, option D is 3.0 x 10-10 m.
For that question I got B.
2. A student wishes to make a measurement of the road distance from his dormitory to the physics building of his university. she uses her car's trip odometer, which measures distance only in units of a tenth of a mile. She makes one trip, and the odometer reads 0.3 mi. What can she say is the distance ?
A. 0.3 mile
B. 0.1 mile
C. 0.2 mile
D. 0.4 mile
I put A but it seems too simple.
3.In the above problem to how many significant figures can she claim she knows the distance?
A. 3
B. 2
C. 1
D. 0
I put C.
4. In the same problem above if she has to know the distance to the physics department to the next significant figure how many round trips to the department should she take ?
A. 100
B. 10
C. 5
D. 3
I'm stuck on this one.
I'm just going to post this again since it keeps cutting my answers off.
correct on 1.
1. To estimate the distance L in a cubic array of water molecules, we need to use the given information and some basic calculations.
We are given that 18 grams of water contains 6.02 x 10^24 molecules. The density of water is also given as 1 g/cm^3.
First, let's find the mass of one water molecule. We can do this by dividing the total mass of water (18 g) by the total number of molecules (6.02 x 10^24):
Mass of one water molecule = 18 g / (6.02 x 10^24) = 2.99 x 10^-24 g
Now, let's find the volume of one water molecule. Since the water molecules are arranged in a cubic array, each molecule will occupy a cube of side length L. The volume of a cube is given by V = L^3, but since we are looking for the volume of a single molecule, we can write it as:
Volume of one water molecule = L^3
Next, we'll use the density of water (1 g/cm^3) to relate the mass and volume of one water molecule:
Density = Mass / Volume
1 g/cm^3 = (2.99 x 10^-24 g) / (L^3)
Finally, we can solve for L:
L^3 = (2.99 x 10^-24 g) / (1 g/cm^3)
Taking the cube root of both sides will give us the value of L:
L = (2.99 x 10^-24 g / 1 g/cm^3)^(1/3)
Now, let's calculate the value of L:
L ≈ 1.44 x 10^-8 cm
Therefore, the answer to the question is B. 1.44 x 10^-8 cm.
2. In this question, the student is using a car's trip odometer that measures distance in units of a tenth of a mile. The student made one trip and the odometer reads 0.3 mi. So, we can conclude that the distance is 0.3 mi.
Therefore, the answer is D. 0.
3. When determining the number of significant figures, we look at the measurement and consider the digits that are known with certainty and one estimated digit. In this case, the distance measurement is 0.3 mi, which has one digit after the decimal point and is followed by a zero.
Therefore, the answer is C. 1.
4. To know the distance to the next significant figure, the student needs to take additional round trips to get more data. In order to move from two significant figures to three, we need to take five round trips.
Therefore, the answer is C. 5.