1A2 Experiments and the Scientific Method

Question 1

Fill in the blank:

After forming a hypothesis, one should design and conduct a/an _________ to test it.

Answer 1

experiment

The experiment provides data that can be analyzed to support or refute the hypothesis.

Question 2

Why are standard units of measurement important in scientific experiments?

Answer 2

They provide a universal language for consistent and comparable data.

Standard units, like meters or kilograms, are defined by the International System of Units (SI).

Question 3

List the seven SI Base Units and their corresponding fundamental measurements.

Answer 3

• Meter (m) – Length
• Kilogram (kg) – Mass
• Second (s) – Time
• Ampere (A) – Electric current
• Kelvin (K) – Temperature
• Mole (mol) – Amount of substance
• Candela (cd) – Luminous intensity

These units form the foundation of the International System of Units (SI) and are used globally in scientific measurements.

Question 4

True or false:

Dimensional analysis ensures that an equation is dimensionally consistent.

Answer 4

True

Dimensional analysis checks if the units on both sides of an equation match, indicating logical correctness. It is also called factor-label method

Question 5

Define:

unit conversion

Answer 5

The process of converting a value from one unit of measurement to another while maintaining its value.

For example, an American scientist may want to convert their data from meters to miles, since Americans are not as familiar with the length of a meter.

Question 6

Fill in the blank:

A ________ _____ is used to convert one unit to another by multiplying by the appropriate ratio of equivalent units.

Answer 6

conversion factor

Conversion factors are ratios that express how many of one unit equals another, like 1km=1000m.

Using consistent conversion factors ensures calculations align with scientific standards.

Question 7

What are some common errors that can occur during unit conversion?

Answer 7

• Rounding errors
• Using Incorrect conversion factors
• Inconsistent units

For example, using the wrong conversion factor when converting kilometers to miles will result in an incorrect answer.

Question 8

What are significant figures?

Answer 8

The digits in a measurement that reflect its accuracy and precision.

Significant figures indicate the precision of a measurement, with more digits showing greater accuracy and detail.

Question 9

What are the rules for determining significant figures?

Answer 9

• All non-zero digits are significant.
• All zeros in between non-zero digits are significant.
• All zeros before the first non-zero digit are NOT significant.
• All zeros to the right of non-zero digits with decimals are significant.
• All zeros after a non-zero non-decimal number are NOT significant.

These rules help determine how much precision is present in a measurement.

Question 10

What is the rule for rounding significant figures?

Answer 10

If the next digit is 5 or greater, round up. If it is less than 5, leave the last significant figure unchanged.

For example, when rounding 3.456 to two significant figures, the third digit (6) is 5 or greater, so you round up the second digit (5) to 6, resulting in 3.5. Rounding ensures the result reflects the measurement’s precision.

Question 11

What is scientific notation?

Answer 11

A way to express very large or small numbers using powers of ten.

Scientific notation simplifies the writing of numbers that are too large or small to be practical for regular use.

Question 12

How do you convert from scientific notation to standard notation?

Answer 12

1. Remove the power of ten (10^x).
2. Move the decimal point x places to the right if the exponent is positive.
3. Move decimal point to the left if the exponent is negative.

Example: 2.304 x 10⁻⁷ becomes 0.0000002304. Moving the decimal to the left makes the number smaller.

Question 13

True or false:

A vector has both magnitude and direction.

Answer 13

True

Vectors are represented by arrows, where the length denotes magnitude and the direction indicates orientation.

Question 14

Fill in the blank:

Vector quantities have both magnitude and ________, while scalar quantities have only magnitude.

Answer 14

direction

Velocity is a vector, while speed is a scalar.

Question 15

What are some examples of scalar quantities?

Answer 15

• Speed
• Temperature
• Time
• Money
• Mass

These quantities do not require direction to describe them.

Question 16

What are some common vector quantities in physics?

Answer 16

• Velocity
• Acceleration
• Force
• Displacement

These quantities require both magnitude and direction.

Question 17

Fill in the blank:

The sum of two vectors can be determined graphically by arranging them ____ ___ _____.

Answer 17

tip to tail

This method involves placing the tail of the second vector at the tip of the first vector to determine the resultant.

Question 18

What is the difference between adding vectors and adding scalars?

Answer 18

When adding vectors, both magnitude and direction must be considered. In contrast, when adding scalars, only their magnitudes are added, as they have no direction

Scalars do not have direction, unlike vectors which have both magnitude and direction.

Question 19

What is the component method of vector addition?

Answer 19

It involves breaking each vector into horizontal and vertical components. The components in each direction are then added separately, and the resulting components are combined to find the total vector.

This method simplifies vector addition, especially in 2D or 3D space.

Question 20

What are the key components of an experimental design?

Answer 20

*Hypothesis
*Variables (independent, dependent, controlled)
*Data collection plan
*Analysis method.

A well-structured design ensures that the experiment can test the hypothesis effectively and reproducibly.

Question 21

Fill in the blanks:

A well-defined data collection plan ensures that measurements are ________ and ________.

Answer 21

accurate and precise

Accuracy reflects how close a measurement is to the true value, while precision indicates the consistency of repeated measurements.

Question 22

Why is it important to clearly define the independent variable in an experiment?

Answer 22

It identifies what is being manipulated to observe its effect on the dependent variable.

This helps establish a cause-and-effect relationship in the investigation. For example, if you change the temperature to see how it affects a liquid’s rate of evaporation, the temperature is the independent variable.

Question 23

What are confounding variables?

Answer 23

Unexpected factors that might influence the relationship between the independent and dependent variables.

Confounding variables can skew results if not controlled. For example, in a study about exercise and weight loss, diet would be a confounding variable if not controlled for.

Question 24

Explain the role of a control group in experimental design.

Answer 24

It provides a baseline to compare the effects of the independent variable.

Control groups help isolate the influence of external factors on the dependent variable.

Question 25

What is the difference between **qualitative** and **quantitative** research?

Answer 25

* Qualitative research focuses **descriptive data**. * Quantitative research relies on **numerical data**. ## Footnote Qualitative research collects descriptive data through methods like interviews, observations, and case studies. For example, collecting *stories* from teachers about their career experiences to understand the challenges and rewards they encounter in the profession. Quantitative research measures numerical data through experiments and surveys. For example, tracking test scores before and after implementing a *new teaching method*.

Question 26

Why is **random sampling** important in research?

Answer 26

To **reduce bias** and **improve the validity** of results. ## Footnote Random sampling ensures every individual in a population has an equal chance of being selected. For example, *randomly selecting* students from a school ensures **fair representation** in a survey on study habits, as it avoids over-representing or under-representing any specific group.

Question 27

What is the difference between **reliability** and **validity** in research?

Answer 27

Reliability refers to the consistency of a measurement—whether it produces the same results under the same conditions. Validity refers to the accuracy of a measurement—whether it actually measures what it is intended to measure. ## Footnote A study can be reliable without being valid, but if a study is valid, it is often reliable.

Question 28

A researcher **observes** that their data points **cluster tightly** together but are consistently far from the true value. What does this indicate?

Answer 28

High precision, low accuracy. ## Footnote For instance, repeatedly measuring a length as 10.5cm when the true value is 12cm demonstrates precision without accuracy.

Question 29

# Fill in the blank: Data **presented** in rows and columns is called a \_\_\_\_\_\_.

Answer 29

table ## Footnote Tables organize information into rows and columns, making it easier to read and compare data.

Question 30

# Fill in the blanks: In a standard Cartesian coordinate system, the x-axis runs \_\_\_\_\_\_\_\_ , while the y-axis runs \_\_\_\_\_\_\_\_ .

Answer 30

horizontally; vertically ## Footnote The orientation of these axes helps in visualizing relationships between variables. Generally, the horizontal axis represents the independent variable and the vertical axis the dependent variable. For example, in a graph tracking speed, time (x-axis) influences speed (y-axis).

Question 31

Which type of **graph** is best for displaying trends or patterns over time?

Answer 31

Line graph ## Footnote Line graphs highlight trends, such as how temperature changes hourly or sales grow monthly.

Question 32

When is it more appropriate to use a **pie chart** instead of a bar graph?

Answer 32

* Use pie charts for **proportions**. * Use bar graphs for **comparisons**. ## Footnote Use a pie chart when showing proportions or percentages of a whole, typically when the data represents parts of a single category. Use a bar graph when comparing different categories or groups, especially when the values are not parts of a whole.

Question 33

# True or false: **Tables** are the best method for analyzing trends over time.

Answer 33

False ## Footnote Line graphs are better for **visualizing trends**, like temperature changes over a week, while tables are used to display raw data.

Question 34

What does a **positive correlation** between two variables indicate?

Answer 34

A **relationship** where as one variable *increases*, the other also *increases*. ## Footnote For instance, the amount of study time and exam scores often show a positive correlation: *studying more* typically results in *higher scores*.

Question 35

What is **extrapolation**?

Answer 35

It is predicting values **beyond** the observed range. ## Footnote For instance, using past population data to **forecast** future growth trends.

Question 36

# Fill in the blanks: The **range** of a dataset is calculated as the difference between the \_\_\_\_\_\_\_\_ and \_\_\_\_\_\_\_\_ values.

Answer 36

highest; lowest ## Footnote The range provides a simple measure of data spread. For example, in the dataset **[3, 7, 10, 15]**, the range is 15 - 3 = **12**.

Question 37

# True or false: The **mean (average)** is a measure of accuracy in an experiment.

Answer 37

False ## Footnote The mean represents the **central tendency** of a data set, but accuracy refers to how close a measurement is to the true value, not the average of multiple measurements.

Question 38

Why is it important to calculate **percent error** in an experiment?

Answer 38

To **measure** how accurate the results are compared to the expected value. ## Footnote For example, if the expected value is 50g and the measured value is 48g, the percent error quantifies the deviation as **4%**.

Question 39

# Define: random error

Answer 39

It refers to **unpredictable** variations in measurements that occur due to small, uncontrollable factors. ## Footnote For example, if you're measuring the length of an object with a ruler, slight differences in how you align the ruler each time could cause random errors in your measurements. Over time, this would lead to small fluctuations between trials.

Question 40

# Fill in the blank: **Proper calibration** prevents systematic \_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_.

Answer 40

errors ## Footnote Regular calibration ensures measurement instruments stay accurate and provides consistency across different experiments.

Question 41

What are effective ways to **minimize errors** in an experiment?

Answer 41

* Increasing sample size * Taking multiple measurements * Calibrating equipment * Using randomized samples ## Footnote These strategies help **minimize** both random and systematic errors improving the overall reliability and validity of results.

Question 42

How do scientists interpret data to **draw conclusions**?

Answer 42

Scientists draw conclusions by analyzing collected data, identifying patterns, and **determining whether the evidence supports or contradicts their hypothesis**. ## Footnote Scientists will look at the evidence that was collected, analyze patterns or trends, then compare to their original hypothesis. Then, scientists will make inferences in order to explain their results.