Chaptest b - Chapter test B for Holt physics - Copyright © by Holt ... - Free Printable

Let's go through each question on the Chapter Test B: The Science of Physics and solve them step by step with explanations.

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1. A hiker uses a compass to navigate through the woods. Identify the area of physics that this involves.

Options:
a. thermodynamics
b. relativity
c. electromagnetism
d. quantum mechanics

Answer: c. electromagnetism

Explanation:
A compass works because it responds to Earth’s magnetic field. The needle of a compass is a small magnet that aligns itself with the planet's magnetic field lines. This behavior is governed by the principles of electromagnetism, one of the fundamental forces in physics.

✔ Correct answer: c

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2. According to the scientific method, how does a physicist formulate and objectively test hypotheses?

Options:
a. by defending an opinion
b. by interpreting graphs
c. by experiments
d. by stating conclusions

Answer: c. by experiments

Explanation:
The scientific method emphasizes objective testing of hypotheses through controlled experiments. Experiments allow scientists to collect data and determine whether their hypothesis is supported or not. Defending opinions (a), interpreting graphs (b), or stating conclusions (d) come *after* experimentation.

✔ Correct answer: c

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3. Diagrams are not designed to

Options:
a. show relationships between concepts.
b. show setups of experiments.
c. measure an event or a situation.
d. label parts of a model.

Answer: c. measure an event or a situation.

Explanation:
Diagrams are visual tools used to illustrate ideas, such as showing relationships (a), experimental setups (b), or labeling components (d). However, they do not provide actual measurements—they are not measuring instruments. Measurements require precise tools like rulers, stopwatches, etc.

✔ Correct answer: c

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4. The most appropriate SI unit for measuring the length of an automobile is the

Options:
a. micron
b. kilometer
c. meter
d. nanometer

Answer: c. meter

Explanation:
- A micron (μm) = 10⁻⁶ m — too small (used for cells or bacteria).
- A nanometer (nm) = 10⁻⁹ m — even smaller (used for atoms).
- A kilometer (km) = 1000 m — too large for a car.
- A meter (m) is ideal for everyday objects like cars (~4–5 meters long).

✔ Correct answer: c

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5. The radius of Earth is 6,370,000 m. Express this measurement in km in scientific notation with the correct number of significant digits.

Given: 6,370,000 m → convert to km

We know:
- 1 km = 1000 m → so divide by 1000:
$$
6,370,000 \div 1000 = 6,370 \text{ km}
$$

Now write in scientific notation:
$$
6,370 = 6.37 \times 10^3 \text{ km}
$$

How many significant digits?
Original number: 6,370,000 — has 3 significant figures (the zeros are placeholders unless specified otherwise). So we keep 3 sig figs: 6.37 × 10³ km.

Options:
a. 6.37 × 10⁶ km → too big
b. 6.37 × 10³ km → ✔ correct
c. 637 × 10³ km → same as 6.37 × 10⁵ → wrong
d. 63.7 × 10⁴ km → same as 6.37 × 10⁵ → wrong

✔ Correct answer: b. 6.37 × 10³ km

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6. Three values were obtained for the mass of a metal bar: 8.83 g; 8.84 g; 8.82 g. The known mass is 10.68 g. The values are

Options:
a. accurate
b. precise
c. both accurate and precise
d. neither accurate nor precise

Analysis:
- Precision: How close the measurements are to each other. These values (8.82, 8.83, 8.84) are very close → high precision.
- Accuracy: How close the measurements are to the true value (10.68 g). All three are around 8.8 g, which is far from 10.68 g → not accurate.

So: precise but not accurate

✔ Correct answer: b. precise

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7. Calculate the following, and express the answer in scientific notation with the correct number of significant figures: 10.5 × 8.8 × 3.14

First, multiply:

Step-by-step:
- 10.5 × 8.8 = 92.4
- 92.4 × 3.14 ≈ ?

Calculate:
$$
92.4 × 3.14 = ?
$$
Break it down:
- 92.4 × 3 = 277.2
- 92.4 × 0.1 = 9.24
- 92.4 × 0.04 = 3.696
Add: 277.2 + 9.24 = 286.44 + 3.696 = 290.136

So result = 290.136

Now apply significant figures rules:
- Multiplication: use the least number of significant figures.
- 10.5 → 3 sig figs
- 8.8 → 2 sig figs
- 3.14 → 3 sig figs

Least is 2 sig figs → answer must have 2 significant figures

Round 290.136 to 2 sig figs:
- 290 → becomes 2.9 × 10² (because 290 rounded to 2 sig figs is 290 → 2.9 × 10²)

Now check options:
a. 2.9 × 10² → ✔ correct
b. 290.136 → too many digits
c. 2.90 × 10² → 3 sig figs → too many
d. 290 → still 2 sig figs, but not in scientific notation properly

Wait: Is 290 considered 2 or 3 sig figs?
- If written as 290 without decimal, it’s ambiguous, but typically 2 sig figs if trailing zero isn't significant.

But scientific notation is clearer.

Best choice: a. 2.9 × 10²

✔ Correct answer: a

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✔ Final Answers:

| Question | Answer |
|--------|--------|
| 1 | c |
| 2 | c |
| 3 | c |
| 4 | c |
| 5 | b |
| 6 | b |
| 7 | a |

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